The Russian army on Friday accused Kyiv forces of striking a jail holding Ukrainian prisoners of war in separatist-controlled eastern Ukraine, saying 40 people died and scores were wounded.

The Russian defence ministry said that the jail in Olenivka in the separatist-held region of Donetsk had been targeted overnight with US-made HIMARS rocket systems.

The Russian defence ministry said that the Ukrainian prisoners of war included members of the Azov battalion, who defended the Azovstal plant in the port city of Mariupol.

Russia describes the former paramilitary unit, which has previous links to far-right groups, as a neo-Nazi organisation.

Russian television showed what appeared to be destroyed barracks and tangled metal beds but no casualties could be seen.

Moscow claimed that the "bloody provocation of the Kyiv regime" was designed to discourage Ukrainian troops from laying down their arms and surrendering.

"This egregious provocation was carried out to intimidate Ukrainian servicemen," the defence ministry said.