The United Nations called on Russia and Ukraine to treat prisoners of war humanely Tuesday, days after recordings emerged that appeared to show military leaders on both sides of the fight calling for the summary execution of prisoners. 

"If verified, the order to summarily execute persons hors de combat, including prisoners of war, followed by their killing or an attempt to do so amounts to a war crime, as does the declaration that no quarter will be given," Ravina Shamdasani, spokesperson for the UN's High Commissioner for Human Rights, said in a statement Tuesday. "We call on Russian and Ukrainian authorities to comply with their obligations under international law to investigate the statements in these recordings and to identify and prosecute those responsible."

Audio first surfaced on multiple Telegram channels Sunday that appeared to show Ukrainian forces ordering the killing of a Russian prisoner of war. 

Yevgeny Prigozhin, who leads the Russian mercenary group Wagner, responded by saying that his forces will kill all rival soldiers in Bakhmut, a city in eastern Ukraine that has been the center of fighting for months. 

"We will kill everyone on the battlefield. Take no more prisoners of war!" Prigozhin said Sunday in a Telegram message, according to Agence France-Presse. 

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The authenticity of the recordings are in dispute, the UN noted. 

The UN Human Rights Monitoring Mission in Ukraine released a report last month that documented 40 summary executions on both sides of the war since Russia invaded in February 2022. Prisoners were also subjected to varying degrees of torture, including beatings, electrocution, shootings, stabbings, and mock executions, the report said. 

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"Almost half of the 229 Russian POWs who we interviewed spoke of being tortured or ill-treated by members of Ukrainian armed forces and the SBU, and to a lesser extent penitentiary staff," Matilda Bogner, a spokesperson for the UN's mission in Ukraine, said in a statement.

"In relation to the treatment of Ukrainian prisoners of war, we are also deeply concerned by the summary execution of 15 Ukrainian prisoners of war shortly after being captured by Russian armed forces. The Wagner Group military and security contractors perpetrated 11 of these executions," Bogner added.

Disturbing videos and photographs have surfaced on social media over the course of the war that show war crimes.

One video earlier this month appeared to show Russian forces beheading a Ukrainian service member with a knife. 

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A disturbing video surfaced on social media earlier this month that appeared to show Russian forces beheading a Ukrainian service member

"There is something that no one in the world can ignore: how easily these beasts kill," Ukrainian President Volodymyr Zelenskyy said in reaction to the beheading video. "This video, the execution of a Ukrainian captive, the world must see it. This is a video of Russia as it is. What kind of creatures they are."