Kyiv said on Tuesday that Russian forces had shot dead five Ukrainian servicemen who had surrendered in the eastern Donetsk region, building on previous war crimes allegations levied against Moscow.
Both Moscow and Kyiv have accused each other's armies of committing atrocities since Russian forces launched their full-scale invasion of Ukraine in February 2022.
Ukrainian prosecutors in the war-battered Donetsk region said the incident had taken place on November 13 near the village of Petrivka in Pokrovsk district.
"Five Ukrainian servicemen retreated and hid in a private house, which was later surrounded by the enemy," the regional prosecutor's office said.
"Russian soldiers took them prisoner and forced them unarmed to come out of the shelter and lie on the ground. After that, the Russian military shot them," the statement said, adding that an investigation had been launched.
There was no immediate response to the claims from Moscow.
The Ukrainian rights ombudsman Dmytro Lubinets said he had contacted the Union Nations and the International Committee of the Red Cross (ICRC) over the allegations.
The UN has documented "numerous violations of international humanitarian law against prisoners of war, including cases of summary execution of both Russian and Ukrainian POWs", a spokeswoman for the UN Human Rights Office told AFP last year.