Amnesty: War crimes rife in Ukraine
Both sides in the conflict in eastern Ukraine are perpetrating war crimes almost daily , including torture and summary killings of prisoners, according to Amnesty International.
The rights group said it had heard accounts from former captives of government and separatist forces of savage beatings, torture with electric shocks, kicking and stabbings.
Amnesty said it interviewed 17 captives of the separatists and 16 held by Ukrainian government forces for its report.
Concern about the treatment of prisoners comes as Ukrainian authorities face scrutiny this week for publicly parading two men they say were Russian soldiers captured while fighting alongside separatists.
Amnesty is urging UN agencies and experts to visit detention sites in Ukraine to meet those being held by both sides.
Hundreds of Ukrainian troops are believed to have been captured by rebel forces in the year-long war that has claimed more than 6,100 lives. Both sides routinely accuse each other of mistreating captives.
Under a February peace agreement, all war prisoners had been due for release in early March, but little progress has been achieved.
"In the shadow of eastern Ukraine's still-smouldering conflict, our on-the-ground research shows that accounts of detainee torture are as commonplace as they are shocking," Amnesty International representative John Dalhuisen said.
The mistreatment catalogúed in the Amnesty report included instances of prisoners being hung from the ceiling, deprived of sleep for days and threatened with death.
"The Ukrainian authorities must investigate all allegations of war crimes and other abuses, open files and collect evidence of abuses by separatist forces and bring to justice all those responsible for perpetrating such heinous acts," Mr Dalhuisen said.
The group is urging UN agencies and experts to visit detention sites in Ukraine to meet those being held by both sides.
Amnesty said the worst abuse tends to occur during the first days of captivity and that groups operating largely outside the chain of command are the most violent.
"The situation on the separatist side is particularly chaotic, with a variety of different groups holding captives in at least a dozen known locations," Amnesty said.
It identified Ukraine's Right Sector nationalist militia as one of the worst culprits on the pro-government side.
"Right Sector has reportedly held dozens of civilian prisoners as hostages, brutally torturing them and extorting large amounts of money from them and their families," the group said.
Amnesty said attempts to get Ukrainian authorities to address complaints over Right Sector have been ignored.
The Ukrainian Security Service said it is open to dialogue with international rights organisations and will meet Amnesty to discuss the report.
Eduard Basurin, a spokesman for rebel forces in the separatist stronghold of Donetsk, denied Amnesty's findings.
"They constantly make these accusations but they are never able to provide any evidence," he said.
But Amnesty said it has corroborated the accounts it collected with evidence such as X-rays of broken bones, medical records and photographs of injuries.
Russian president Vladimir Putin's spokesman said later that Moscow is making efforts towards the release of the two Russians put on show in Ukraine, but declined comment on claims that they are soldiers.
In video published by the newspaper Novaya Gazeta, the two men repeated assertions that they were on active duty with the Russian military in rebellious eastern Ukraine when they were captured on Saturday.
Russia consistently denies Ukrainian and Western allegations that it is supporting eastern Ukraine's separatists with troops and equipment. The Defence Ministry said this week that the two men had been soldiers but were no longer serving.
Kremlin spokesman Dmitry Peskov said Russia "is taking all necessary measures to get them out of captivity" but that whether they were soldiers "is not a subject for the presidential administration".