Rights group Amnesty International called on Ukraine's leaders yesterday to act against "abuses and war crimes" committed by volunteer militias fighting against proRussian rebels in the east.

Amnesty said it had documented a growing number of abuses, “including abductions, unlawful detention, ill-treatment, robbery, extortion, and possible executions" by one pro-Kiev battalion fighting in the Lugansk area.

Prime Minister Arseniy Yatsenyuk, who met Amnesty chief Salil Shetty during his visit to Kiev, pledged that the government would hold those responsible to account, saying "all perpetrators of crimes are equal before the law".

In a report on the Ukraine conflict on Sunday, Amnesty said both warring sides were committing human rights abuses and war crimes, in particular accusing Russia of "fuellingseparatist crimes".

But it also highlighted violations by the army and the numerous volunteer battalions fighting against the pro-Kremlin separatists in control of large parts of eastern Ukraine.

"The failure to stop abuses and possible war crimes by volunteer battalions risks significantly aggravating tensions in the east of the country and undermining the proclaimed intentions of the new Ukrainian authorities to strengthen and uphold the rule of law more broadly," Shetty said yesterday.

Amnesty highlighted the actions of the Aidar battalion in the northern Lugansk area, one of about 30 volunteer militias loosely integrated into Ukrainian security forces.

It recounted cases where the fighters abducted local men accused of collaborating with the rebels, beating them and holding them in makeshift detention centres and often demanding ransoms fortheirreleaseorstealingtheirvaluables.