Syria was once famed for its spectacular heritage sites, but new satellite imagery shows at least 290 cultural monuments have been destroyed or damaged since the outbreak of war in 2011. Syria is home to archaeological treasures that span thousands of years of written history, from the Roman ruins in the desert oasis of Palmyra to the towering Crusader castle known as the Crac des Chevaliers near the Mediterranean coast. The nation's capital, Damascus, is also one of the oldest continually inhabited cities in the world. As evidence emerges of the extent of the devastation caused by the civil war, experts also claim ancient treasures dating back three millennia have been plundered and are being sold on the British black market and eBay to fund Islamic State terrorists. Scroll down for video . The UN agency released close-ups of satellite-detected images of the shrine of Uwais al-Qurani and Ammar bin Yasser in the Syrian city of Raqa, showing how whole buildings have been flattened during the conflict . The historic heart of the northern Syrian city of Aleppo has also been destroyed in large parts by ongoing shelling since the conflict first broke out in 2011 . These satellite images reveal the scale of destruction that Isis looters continue to inflict on archaeological sites within the Syrian warzone to turn a profit and buy weapons. Classical-period site Dura Europos in eastern Syria, which was founded in the third century BC and boasts one of the world's earliest churches, is one of dozens of sites now covered in looters' pits. Valuable artefacts such as Roman busts are now being touted in Britain and the US and a Hellenistic coin collection from Syria has even appeared on eBay, according to experts. Christopher Marinello, who founded Art Recovery International, said: ‘We have seen a great deal of evidence of ancient Syrian artefacts making their way into the UK and the US,’ he said. ‘Recently a middle-man approached me with a catalogue of important objects we believe were taken from sites within the Syrian war zone. Some with evidence of dirt still on them were being offered for sale. 'Any respected dealers should not touch them, as dealing in looted works from war zones could directly fund terrorism. ‘We feel that Syria has potential for the worst looting we have ever witnessed and it represents the biggest cultural threat since the Second World War.’ Syrian archaeologist Amr Al Azm said he recently saw coins dating from 121BC, believed to have been smuggled from Syria, being sold on eBay with a guide price of £73. ‘The advert said the coins came with some original find dirt, which was a real give away,’ said the professor of Middle East history at Shawnee State University, Ohio. ‘These types of objects are now starting to appear much more online, especially on the dark net.’ Unitar also provided satellite images of Necropolis, in the ancient oasis city of Palmyra, showing how it had changed between 2009 and 2014 . The archaeological site of Dura-Europos near the western Syrian village of Salhieh on September 4, 2011 (L) and on on April 2, 2014 (R) appears to show significant damage to the landscape as a result of the war . A picture taken on March 14, 2014, shows the courtyard of the sanctury of Baal in the ancient oasis city of Palmyra, an ancient Aramaic city in central Syria . Rebel fighters fire machine guns on the frontline during the battle against pro-government forces for control of the Handarat region, just north of Aleppo . Ancient treasures  have been plundered from Syrian sites inlcuding in Palmyra, northeast of Damascus (pictured with a Syrian policeman) and are being sold on the British black market and eBay . Looters tasked by Isis have sunk several large pits in the ancient Mesopotamian city Mari, eastern Syria, which dates back to 2900 BC. They have destroyed key structures within the famous 'palace of Zimri-lim', which was stormed by Hammurabi of Babylon in the mid-18th century BC. ‘The situation is much more critical now particularly in areas under the control of Isis,' said Professor Al Azm, who is part of a group that monitors the scale of looting using satellite imagery and undercover activists on the ground. 'It is now becoming a lucrative enough enterprise for them to kill to preserve it. ‘At first when Isis entered these areas, they sanctioned the plundering of ancient sites as long as they were given a percentage and this encouraged more people to dig up the sites. ‘But now Isis has started to bring in its own contractors. They are using heavy machinery and bulldozers to excavate, destroying these important sites. ‘The cultural heritage of Syria is being pillaged at an ever-accelerating rate. To see it destroyed like this for the sake of profit is very upsetting and distressing. ‘When you destroy this cultural heritage and the shared past, then you also destroy any chance of a future.’ The renowned Crusader castle Krak des Chevaliers near the Syria-Lebanon border has also been damaged extensively in the conflict . The minaret of a famed 12th century Umayyad mosque is shown before it was destroyed by shelling in the northern city of Aleppo . More than 80 archaeologists and scholars from around the world have signed an open letter calling on the United Nations Security Council to ban illicit trade in Syrian antiquities. Edouard Planche from UNESCO’s Culture Sector is supporting the ban and said he was calling upon those in the arts market to not trade in Syrian antiquities as it could fund terrorism. Richard Ellis, who set up Scotland Yard's Art and Antiquities Squad, said many valuable objects are going into vaults in Zurich and Geneva where they will be held for several years. ‘I’ve seen reports of increased objects entering the US market and that is probably because they monitor the input so rigorously. ‘At the moment if artefacts enter the British market, they will be the everyday items. The important objects such as the mosaic floors we will only start seeing in 10 or 15 years time after the conflict. ‘In Britain the policing of illicit trade in antiquities is totally inadequate. There are a maximum of four officers covering that type of crime, so they are very stretched.’ A new report by the United Nations Institute for Training and Research (Unitar) has revealed the extent to which some of the world's most historic sites have been damaged. It has long been known that Syria's archaeological sites have been looted and its historic buildings damaged since the country's conflict began in March 2011. However, analysing satellite images of 18 cultural areas, Unitar determined that 24 sites were totally destroyed, another 104 sites were severely damaged, 85 moderately damaged and 77 possibly damaged. The 12th century Krak des Chevaliers castle is among the nearly 300 cultural sites that have been damaged by the ongoing violence in the country . The ancient oasis city of Palmyra,  northeast of Damascus, is considered one of Syria's most important cultural sites . The evidence provides 'alarming testimony of the ongoing damage that is happening to Syria's vast cultural heritage', Unitar said. 'National and international efforts for the protection of these areas need to be scaled up in order to save as much as possible of this important heritage to human-kind.' Unesco World Heritage sites in Aleppo, Damascus, Palmyra and the Crac des Chevaliers have all sustained major damage, according to Unitar. Sites across the country have been exposed to different threats. In some places, shelling and other military activity are responsible for the destruction, while in other places illegal excavations and civilian construction are to blame. The report offers before and after photographs from several sites that indicate the scale of the loss. Photos of Aleppo show grey craters and mounds of rubble around the city's famed citadel where historic buildings, including the Carlton hotel, used to be. Heavy damage is also evident to the Umayyad Mosque, which has lost its 11th-century minaret. Images from the ancient city of Dura-Europos and Palmyra show extensive looting, with the ground peppered with holes from unauthorised digging. A Home Office spokesman said that Border Force had not come into contact with any items from Syria, while eBay said: 'We provide guidance to eBay sellers in our Help section to make sure that any artefacts they may try to sell comply with the guidelines issued by the authorities, and are always ready and willing to investigate any listings causing concern. 'We work with experts and will remove items from sale based on their advice.'
New satellite images show extensive damage to most treasured sites .
UN report confirms 24 sites completely destroyed in civil war .
Archeological sites ruined and buildings damaged in violent clashes .
Syria was once famed for its spectacular heritage sites, but new satellite imagery shows at least 290 cultural monuments have been destroyed or damaged since the outbreak of war in 2011. Syria is home to archaeological treasures that span thousands of years of written history, from the Roman ruins in the desert oasis of Palmyra to the towering Crusader castle known as the Crac des Chevaliers near the Mediterranean coast. The nation's capital, Damascus, is also one of the oldest continually inhabited cities in the world. As evidence emerges of the extent of the devastation caused by the civil war, experts also claim ancient treasures dating back three millennia have been plundered and are being sold on the British black market and eBay to fund Islamic State terrorists. Scroll down for video . The UN agency released close-ups of satellite-detected images of the shrine of Uwais al-Qurani and Ammar bin Yasser in the Syrian city of Raqa, showing how whole buildings have been flattened during the conflict . The historic heart of the northern Syrian city of Aleppo has also been destroyed in large parts by ongoing shelling since the conflict first broke out in 2011 . These satellite images reveal the scale of destruction that Isis looters continue to inflict on archaeological sites within the Syrian warzone to turn a profit and buy weapons. Classical-period site Dura Europos in eastern Syria, which was founded in the third century BC and boasts one of the world's earliest churches, is one of dozens of sites now covered in looters' pits. Valuable artefacts such as Roman busts are now being touted in Britain and the US and a Hellenistic coin collection from Syria has even appeared on eBay, according to experts. Christopher Marinello, who founded Art Recovery International, said: ‘We have seen a great deal of evidence of ancient Syrian artefacts making their way into the UK and the US,’ he said. ‘Recently a middle-man approached me with a catalogue of important objects we believe were taken from sites within the Syrian war zone. Some with evidence of dirt still on them were being offered for sale. 'Any respected dealers should not touch them, as dealing in looted works from war zones could directly fund terrorism. ‘We feel that Syria has potential for the worst looting we have ever witnessed and it represents the biggest cultural threat since the Second World War.’ Syrian archaeologist Amr Al Azm said he recently saw coins dating from 121BC, believed to have been smuggled from Syria, being sold on eBay with a guide price of £73. ‘The advert said the coins came with some original find dirt, which was a real give away,’ said the professor of Middle East history at Shawnee State University, Ohio. ‘These types of objects are now starting to appear much more online, especially on the dark net.’ Unitar also provided satellite images of Necropolis, in the ancient oasis city of Palmyra, showing how it had changed between 2009 and 2014 . The archaeological site of Dura-Europos near the western Syrian village of Salhieh on September 4, 2011 (L) and on on April 2, 2014 (R) appears to show significant damage to the landscape as a result of the war . A picture taken on March 14, 2014, shows the courtyard of the sanctury of Baal in the ancient oasis city of Palmyra, an ancient Aramaic city in central Syria . Rebel fighters fire machine guns on the frontline during the battle against pro-government forces for control of the Handarat region, just north of Aleppo . Ancient treasures have been plundered from Syrian sites inlcuding in Palmyra, northeast of Damascus (pictured with a Syrian policeman) and are being sold on the British black market and eBay . Looters tasked by Isis have sunk several large pits in the ancient Mesopotamian city Mari, eastern Syria, which dates back to 2900 BC. They have destroyed key structures within the famous 'palace of Zimri-lim', which was stormed by Hammurabi of Babylon in the mid-18th century BC. ‘The situation is much more critical now particularly in areas under the control of Isis,' said Professor Al Azm, who is part of a group that monitors the scale of looting using satellite imagery and undercover activists on the ground. 'It is now becoming a lucrative enough enterprise for them to kill to preserve it. ‘At first when Isis entered these areas, they sanctioned the plundering of ancient sites as long as they were given a percentage and this encouraged more people to dig up the sites. ‘But now Isis has started to bring in its own contractors. They are using heavy machinery and bulldozers to excavate, destroying these important sites. ‘The cultural heritage of Syria is being pillaged at an ever-accelerating rate. To see it destroyed like this for the sake of profit is very upsetting and distressing. ‘When you destroy this cultural heritage and the shared past, then you also destroy any chance of a future.’ The renowned Crusader castle Krak des Chevaliers near the Syria-Lebanon border has also been damaged extensively in the conflict . The minaret of a famed 12th century Umayyad mosque is shown before it was destroyed by shelling in the northern city of Aleppo . More than 80 archaeologists and scholars from around the world have signed an open letter calling on the United Nations Security Council to ban illicit trade in Syrian antiquities. Edouard Planche from UNESCO’s Culture Sector is supporting the ban and said he was calling upon those in the arts market to not trade in Syrian antiquities as it could fund terrorism. Richard Ellis, who set up Scotland Yard's Art and Antiquities Squad, said many valuable objects are going into vaults in Zurich and Geneva where they will be held for several years. ‘I’ve seen reports of increased objects entering the US market and that is probably because they monitor the input so rigorously. ‘At the moment if artefacts enter the British market, they will be the everyday items. The important objects such as the mosaic floors we will only start seeing in 10 or 15 years time after the conflict. ‘In Britain the policing of illicit trade in antiquities is totally inadequate. There are a maximum of four officers covering that type of crime, so they are very stretched.’ A new report by the United Nations Institute for Training and Research (Unitar) has revealed the extent to which some of the world's most historic sites have been damaged. It has long been known that Syria's archaeological sites have been looted and its historic buildings damaged since the country's conflict began in March 2011. However, analysing satellite images of 18 cultural areas, Unitar determined that 24 sites were totally destroyed, another 104 sites were severely damaged, 85 moderately damaged and 77 possibly damaged. The 12th century Krak des Chevaliers castle is among the nearly 300 cultural sites that have been damaged by the ongoing violence in the country . The ancient oasis city of Palmyra,  northeast of Damascus, is considered one of Syria's most important cultural sites . The evidence provides 'alarming testimony of the ongoing damage that is happening to Syria's vast cultural heritage', Unitar said. 'National and international efforts for the protection of these areas need to be scaled up in order to save as much as possible of this important heritage to human-kind.' Unesco World Heritage sites in Aleppo, Damascus, Palmyra and the Crac des Chevaliers have all sustained major damage, according to Unitar. Sites across the country have been exposed to different threats. In some places, shelling and other military activity are responsible for the destruction, while in other places illegal excavations and civilian construction are to blame. The report offers before and after photographs from several sites that indicate the scale of the loss. Photos of Aleppo show grey craters and mounds of rubble around the city's famed citadel where historic buildings, including the Carlton hotel, used to be. Heavy damage is also evident to the Umayyad Mosque, which has lost its 11th-century minaret. Images from the ancient city of Dura-Europos and Palmyra show extensive looting, with the ground peppered with holes from unauthorised digging. A Home Office spokesman said that Border Force had not come into contact with any items from Syria, while eBay said: 'We provide guidance to eBay sellers in our Help section to make sure that any artefacts they may try to sell comply with the guidelines issued by the authorities, and are always ready and willing to investigate any listings causing concern. 'We work with experts and will remove items from sale based on their advice.'
devastation caused by the civil war, experts also also been destroyed in large parts by ongoing net.’ Unitar also provided satellite images of appears to show significant damage to the looted and its historic buildings damaged since cultural areas, Unitar determined that 24 sites