A still image taken from a video released by Islamic State-affiliated Amaq news agency, on December 11, 2016, purports to show an Islamic State fighter shooting near what is said to be Palmyra. Handout via REUTERS TV

BEIRUT (Reuters) - The Syrian Observatory for Human Rights said there had been a suspected gas attack in Islamic State-held territory near Palmyra on Monday, amid heavy aerial bombardment of the same area which together killed at least 53 people.

Citing local sources near the site of the attack in eastern Hama province, northwest of the ancient city of Palmyra, the Observatory said there were cases of suffocation and that dozens had been wounded during heavy rocket fire on the area.

The dead included 28 children, the Observatory said.

Local sources had reported seeing dead bodies with no visible injuries, said the Observatory, a British-based group that monitors the war in Syria through a network of contacts across the country.

The reported attack came from the air and took place near the town of Uqairabat, which lies on a main road leading south into Palmyra from government-held territory, the Observatory said, without specifying who might have been responsible.

Amaq, a news service linked to Islamic State, said in an online statement that 20 people had died and around 200 were injured from breathing problems "as a result of a Russian air attack with sarin gas".

Ahmad al-Dbis, of the Union of Medical Care and Relief Organizations (UOSSM), said about 86 people had died, and about 250 were injured in the attacks on Monday.

UOSSM is a coalition of international aid agencies which funds hospitals in Syria. It used to work with staff in the area of the attack before Islamic State took over.

Both the Syrian army and Russia have denied using chemical weapons.

U.N. investigators established that sarin gas was used in parts of the rebel-held Ghouta suburbs of the Syrian capital Damascus in 2013. The United States accused Syria's government of conducting the attack, which it estimated killed around 1,400 people, but Damascus denied responsibility and blamed rebels.

A United Nations investigation this year found that the Syrian military had used chlorine in attacks on rebels and that Islamic State had also used chemical weapons in attacks.

Damascus has said that the conclusions of that investigation were wrong.

On Sunday, Islamic State militants recaptured Palmyra despite dozens of Russian air strikes attempting to push them back. It had previously been driven from the city in March. </s> Russia’s Defense Ministry says it is investigating reports that ISIS leader Abu Bakr al-Baghdadi was killed in one of its airstrikes in Syria last month.

The airstrike on May 28 was carried out on the outskirts of the militant group’s de facto capital Raqqa, on a command post where ISIS leaders were meeting, according to Russian state media reports.

 “According to information, which is being verified via different channels, the meeting was also attended by the (ISIS) leader Ibrahim Abu Bakr al-Baghdadi, who was eliminated in the strike,” the ministry said, according to the TASS report in English. Other state media reported that more than 300 “terrorists” were killed in the strike. </s> Syrian air defences shot down eight missiles after a major air base in central Syria was struck in the early hours of Monday, Syrian state television reported. The state broadcaster said explosions were heard at the T-4 airfield near Homs, which is close to the ancient city of Palmyra in central Syria. It said there were several dead and wounded. Syrian state media said they were suspected to be U.S. strikes but U.S. officials said that the U.S. military had not launched air strikes.

U.S. President Donald Trump said earlier on Sunday there would be a “big price to pay” after medical aid groups reported dozens of people were killed by poison gas in a besieged rebel-held town in Syria. The Syrian state denied government forces had launched any chemical attack. Russia, President Bashar al-Assad’s most powerful ally, called the reports fake.
Russian airstrikes against ISIS in Palmyra kill 5 people.