Russian forces are holding 11 mayors of Ukrainian local areas captive and have killed one mayor in detention, Ukrainian Deputy Prime Minister Iryna Vereshchuk said on Sunday.
In a message posted to social media, Vereshchuk said that 11 local mayors from Kyiv, Kherson, Mykolaiv and the Donetsk regions "are in Russian captivity."
She added that Ukraine will "inform the International Committee of the Red Cross, the UN and other organizations about their captivity."
Vereshchuk said the Ukrainian government learned on Saturday that Olga Sukhenko, the mayor of Motyzhyn -- a village in the Kyiv region -- was killed in captivity by Russian forces.
This is a war crime, those responsible will be punished in line with international humanitarian law," Vereshchuk said, adding that Ukraine will push to ensure "our civilians, our mayors, priests, journalists, and activists are liberated" from detention.
CNN could not independently verify those claims. Russian forces have detained local government officials in a number of instances around Ukraine.
The bodies of at least 20 civilian men have been found lying strewn across the street in the town of Bucha, northwest of Kyiv following the withdrawal of Russian forces from the area in shocking images released by AFP on Saturday.
CNN has requested comment from the Russian defense ministry regarding allegations of the execution of civilians in the Kyiv region and other parts of Ukraine.