WASHINGTON - The US justice chief on Wednesday branded Yevgeny Prigozhin, head of Russia’s mercenary Wagner military force fighting in Ukraine, a war criminal.

Attorney-General Merrick Garland told a Senate hearing that the Justice Department is helping Ukraine investigate war crimes allegedly committed since Russia’s invasion, including by the semi-private Wagner military group.

“Mr Prigozhin, who runs this thing, is in my view a war criminal,” Mr Garland told the hearing.

“Maybe that’s inappropriate for me to say as a judge, before getting all the evidence. But I think we have more than sufficient evidence at this point for me to feel that way.

“That group, which is responsible for the attacks on the Ukrainians in the Donbas, including by bringing in prisoners from Russian prison camps – it’s just an unfathomable what they are doing.”

Ukraine’s prosecutor-general Andriy Kostin has said that Kyiv is investigating Mr Prigozhin for war crimes, and Mr Garland said the United States is aiding Ukraine in its probes.

Mr Prigozhin has been a close ally of Russian President Vladimir Putin, and although Wagner operates mostly independently from the Russian army, it has had a key role in the assault on Ukraine.

In January, the United States formally designated Wagner as a transnational criminal organisation, putting it in league with Italian mafia groups and Japanese and Russian organised crime.

The designation allows wider sanctions on the group’s sprawling global network, which includes mercenary operations as well as businesses in Africa.

US legislators are pressing the administration of President Joe Biden to designate Wagner a terrorist group.

Mr Prigozhin was indicted by the justice department in 2018 for interference in US elections by the St Petersburg-based Internet Research Agency, which he also controls. AFP