Ukraine says Russian forces have 'abducted' 11 mayors

"Up to today, 11 heads of local communities in the regions of Kyiv, Kherson, Kharkiv, Zaporizhzhia, Mykolaiv and Donetsk are in captivity,"  she said in a video message posted on her Telegram account.

"We are informing the International Committee of the Red Cross (ICRC), the UN, all possible organisations, just like for the other civilians who have disappeared."

Vereshchuk urged "everyone to do everything in their power to get them back."

The deputy prime minister announced the that Olga Sukhenko, head of the village of Motyjin, west of Kyiv, and her husband had been "killed in captivity" by Russian soliders.

Their abduction had been announced by prosecutors on March 26.

The European Union has condemned the kidnapping of several mayors in Russian-occupied territory, including the mayor of the southern town of Melitopol, who was freed in an exchange for several captured Russians.

Human Rights Watch on Sunday said it had documented several cases of Russian troops committing possible war crimes against civilians in occupied areas of the Chernigiv, Kharkiv, and Kyiv.

These included a case of repeated rape, and two cases of summary execution -- one of six men, the other of one.

Soldiers were also implicated in looting, including food, clothing, and firewood, the rights group added.