The International Committee of the Red Cross (ICRC) said it had not yet obtained permission to visit the Olenivka prison where Ukrainian prisoners of war died in a strike on the facility, reported DW, quoting agencies.
In a statement, the ICRC said, "As of yet, we have received no official confirmation granting us access to visit the site or the prisoners of war affected by the attack, and, to date, our offer of material assistance has not been accepted."
In a statement late Saturday, the Russian Ministry of Defense said representatives from the UN and the ICRC had been invited to tour the area.
Kyiv has blamed the strike on Moscow which has, in turn, suggested Ukraine was behind the strike on the prison in a Russian-occupied part of eastern Ukraine.
The Russian army said 50 people died and 73 were wounded in the strike. Russian-back forces in the Donetsk region said 53 people had died.
Ukrainian President Volodymyr Zelensky said the bombing left "more than 50 dead" was a "deliberate Russian war crime."