A mother of a Ukrainian rebel who was captured during clashes with pro-Russian separatists claims she has been sent his severed head in a wooden box. Images of what are believed to be the heads of two hostages began circulating on social media today. And in a horrifying turn of events, the woman identified one of them as her son, who she confirmed had been fighting in Donetsk. Scroll down for video . Members of the Ukrainian national guard stand at a checkpoint nearby the town of Slavyanoserbsk, in Luhansk region. A report by Amnesty International is believed to have evidence of war crimes committed by both sides . Ukraine's President Petro Poroshenko claims Russia has removed the bulk of its forces from the region, however there is a still a heavy military presence, with checkpoints in Slavyanoserbsk heavily guarded . According to Newsweek Europe, she said she had received her son’s head in the post and blamed nationalist volunteers for the death. The shocking report came as Amnesty International claimed they have documented evidence of war crimes by both sides in the conflict in eastern Ukraine. The human rights group's secretary general, Salil Shetty, told a news conference in Moscow that some separatists, backed by Russian troops, and Ukraine's Aidar battalion had committed human rights abuses in the five-month-old conflict. Citing satellite imagery as well as witnesses' accounts, Shetty said Russia's involvement in the violence in eastern Ukraine made it a side in the conflict which could make it liable if war crimes are established. Tatyana Grigorivna (left), begs for help to locate her son, Nikolai, (right) who has disappeared from the town of Alovaisk which was damaged during heavy fighting . 'We have repeatedly raised the issue of war crimes and in our most recent reports we have documented evidence of war crimes from both sides,' said Shetty, repeating the allegations in the Russian capital, where authorities have denied their involvement in the conflict in eastern Ukraine. Shetty said the organisation had requested meetings with President Vladimir Putin and Foreign Minister Sergei Lavrov but neither had agreed to meet him or answered the allegations. Russia has denied it is a party to the conflict and has dismissed accusations that it has sent soldiers and weapons to support the separatists. Shetty said human rights abuses, including beatings and abductions, had been carried out by separatists 'who we now know have been backed by Russian forces' and by Ukraine's Aidar Battalion, a volunteer territorial defence group. He also called for an investigation into allegations from both sides of indiscriminate mortar fire which he said had led to more than 1,000 civilian deaths. Ukraine's President, Petro Portoshenko, today promised legislation  to offer greater autonomy to pro-Russian eastern regions, which have been the focus of fighting for five months. He said the regions would remain part of Ukraine and rejected the idea of federalisation, something both Russia and the Russian-backed separatists are still pushing for even after a cease-fire that began Friday. Mr Portoshenko added that the bulk of Russia's forces had been removed from the country, renewing hopes for a peace drive. A separatist fighter, part of a detail guarding an aid delivery, stands near a building damaged during heavy fighting in Aloviask . Despite a declared ceasefire between separatists forces and the Ukrainian military, tensions on the ground are still high, especially in Donetsk . Heavily-armed members of the Ukrainian national guard stand at a checkpoint nearby the town of Slavyanoserbsk in the Lugansk region . Ukrainian volunteers unload food for refugees in the southern coastal town of Mariupol .
Woman claims she was sent her son's severed head in a wooden box .
Came after images of two beheaded hostages circulated on social media .
Organisation say group of Aidar rebels have committed widespread abuse .
It includes 'unlawful detention, abduction, and possible executions'
Report also describes atrocities by pro-Russian militants in eastern Ukraine .
Highlights the brutality of the conflict which has cost 3,000 lives so far .
A mother of a Ukrainian rebel who was captured during clashes with pro-Russian separatists claims she has been sent his severed head in a wooden box. Images of what are believed to be the heads of two hostages began circulating on social media today. And in a horrifying turn of events, the woman identified one of them as her son, who she confirmed had been fighting in Donetsk. Scroll down for video . Members of the Ukrainian national guard stand at a checkpoint nearby the town of Slavyanoserbsk, in Luhansk region. A report by Amnesty International is believed to have evidence of war crimes committed by both sides . Ukraine's President Petro Poroshenko claims Russia has removed the bulk of its forces from the region, however there is a still a heavy military presence, with checkpoints in Slavyanoserbsk heavily guarded . According to Newsweek Europe, she said she had received her son’s head in the post and blamed nationalist volunteers for the death. The shocking report came as Amnesty International claimed they have documented evidence of war crimes by both sides in the conflict in eastern Ukraine. The human rights group's secretary general, Salil Shetty, told a news conference in Moscow that some separatists, backed by Russian troops, and Ukraine's Aidar battalion had committed human rights abuses in the five-month-old conflict. Citing satellite imagery as well as witnesses' accounts, Shetty said Russia's involvement in the violence in eastern Ukraine made it a side in the conflict which could make it liable if war crimes are established. Tatyana Grigorivna (left), begs for help to locate her son, Nikolai, (right) who has disappeared from the town of Alovaisk which was damaged during heavy fighting . 'We have repeatedly raised the issue of war crimes and in our most recent reports we have documented evidence of war crimes from both sides,' said Shetty, repeating the allegations in the Russian capital, where authorities have denied their involvement in the conflict in eastern Ukraine. Shetty said the organisation had requested meetings with President Vladimir Putin and Foreign Minister Sergei Lavrov but neither had agreed to meet him or answered the allegations. Russia has denied it is a party to the conflict and has dismissed accusations that it has sent soldiers and weapons to support the separatists. Shetty said human rights abuses, including beatings and abductions, had been carried out by separatists 'who we now know have been backed by Russian forces' and by Ukraine's Aidar Battalion, a volunteer territorial defence group. He also called for an investigation into allegations from both sides of indiscriminate mortar fire which he said had led to more than 1,000 civilian deaths. Ukraine's President, Petro Portoshenko, today promised legislation  to offer greater autonomy to pro-Russian eastern regions, which have been the focus of fighting for five months. He said the regions would remain part of Ukraine and rejected the idea of federalisation, something both Russia and the Russian-backed separatists are still pushing for even after a cease-fire that began Friday. Mr Portoshenko added that the bulk of Russia's forces had been removed from the country, renewing hopes for a peace drive. A separatist fighter, part of a detail guarding an aid delivery, stands near a building damaged during heavy fighting in Aloviask . Despite a declared ceasefire between separatists forces and the Ukrainian military, tensions on the ground are still high, especially in Donetsk . Heavily-armed members of the Ukrainian national guard stand at a checkpoint nearby the town of Slavyanoserbsk in the Lugansk region . Ukrainian volunteers unload food for refugees in the southern coastal town of Mariupol .
claims she has been sent his severed head in a wooden box. Images of what are believed to be the heads of two hostages began circulating on social involvement in the conflict in eastern Ukraine. Russian forces' and by Ukraine's Aidar Battalion, a volunteer territorial defence group. He also to pro-Russian eastern regions, which have been