United Nations experts on Tuesday called for an independent investigation into possible war crimes and crimes against humanity by government forces and Russian private military contractor Wagner Group in Mali.

Mali, whose government took power in a 2021 military coup, have previously said Russian forces in the West African country are not mercenaries but trainers helping local troops with equipment bought from Russia.

Western powers say the Russian forces in Mali include Wagner Group contractors.

“Since 2021, the experts have received persistent and alarming accounts of horrific executions, mass graves, acts of torture, rape and sexual violence, pillaging, arbitrary detentions and enforced disappearances perpetrated by Malian armed forces and their allies,” said the statement from the independent experts.

Mali’s army spokesperson did not immediately respond to a request for comment. Russian President Vladimir Putin said last year that the Russian state had nothing to do with Russian military contractors working in Mali, adding that the African country had the right to work with private Russian firms.

Reuters has contacted Wagner for comment.

Mali is engaged in a fight against militants linked to al Qaeda and Islamic State who have waged a decade-long insurgency that has spread to neighbouring countries.

The statement mentioned Wagner Group by name, and described credible reports of the involvement of military personnel believed to belong to the group in a massacre of hundreds of people in March.

Survivors have said white mercenaries suspected to be Russians took part in the massacre in Moura, a market town in central Mali. The incident sparked international uproar and prompted the UN to open an earlier investigation.

Mali’s army has denied any wrongdoing in Moura and said it killed 203 militants there during what it described as a military operation.

Wagner Group has attracted international attention over its prominent role in fighting during Russia’s invasion of Ukraine. Washington last week designated Wagner as a transnational criminal organization responsible for widespread human rights abuses.