Ukraine rebels 'executed soldiers'
Amnesty International has obtained evidence that Russian-backed separatists in east Ukraine executed several captured government soldiers in gross violation of international humanitarian law.
Amnesty said that footage viewed by the group shows at least four Ukrainian soldiers now confirmed dead being interrogated by rebel militia.
It said pictures showing bullet wounds to the soldiers' heads and bodies appeared to show they had died as the result of execution-style killings.
Hundreds of Ukrainian troops are believed to have been captured by rebel forces over the course of a year-long war that has claimed more than 6,000 lives.
Both sides accuse one another of mistreating captives. Under a February peace agreement, all prisoners had been due for release in early March but little progress has been achieved.
Eduard Basurin, a spokesman for rebel forces, denied the claims, saying that footage of soldiers being taken prisoner could not serve as evidence.
"Accusations without facts are nothing," Basurin told the Associated Press. "Nobody has shot anybody."
Amnesty said claims of summary killings should be thoroughly and impartially investigated and that perpetrators should be prosecuted in trials by recognised authorities.
"The torture, ill-treatment and killing of captured, surrendered or wounded soldiers are war crimes," Denis Krivosheev, Europe and Central Asia deputy director at Amnesty International, said in the statement.
The English-language Kyiv Post newspaper earlier this week managed to contact a rebel unit commander, Arseniy Pavlov, who is believed to be a Russian national, to respond to widely aired claims he was responsible for killing captives.
In the telephone interview, which has been uploaded to YouTube, Pavlov responds - before hanging up - that he personally shot dead 15 Ukrainian servicemen.
"This chilling 'confession' from a separatist fighter, alongside video evidence and testimony from witnesses, and the mounting evidence of abuses of captives by both sides, highlights the urgent need for an independent investigation into this and all other allegations of abuses in this conflict which began a year ago," Mr Krivosheev said.
Speaking to the AP, Basurin said instances of mistreatment of Ukrainian soldiers captured on video had taken place, but rejected suggestions that separatist fighters were responsible for extrajudicial killings.
Basurin said that Pavlov's remarks to Kyiv Post did not serve as proof of any misdeeds.