By Oleksandr Kozhukhar

KYIV, Feb 4 (Reuters) - Ukraine has brought home 12 children who were forcefully taken by Russia, Ukrainian President Volodymyr Zelenskiy's chief of staff said.

"As part of the initiative of the President of Ukraine Bring Kids Back UA, it was possible to return home 12 children who were under the pressure of the Russian occupation," Andriy Yermak wrote on his Telegram messaging app late on Monday.

The Bring Kids Back UA programme under Zelenskiy says it is an initiative to return home all children forcefully deported from Ukraine.

Among those returned was a 16-year-old who lost her mother, a 17-year-old called up by the Russian army and an eight-year-old girl, Yermak said.

The press office of Russia's Commissioner for Children's Rights, Maria Lvova-Belova, said it had no information about the 12 children.

It told Reuters by email that the commissioner's office took part in family reunifications with Ukraine with the involvement of international mediators when "additional efforts are required to facilitate movement and resolve legal issues."

"Other cases may occur within the framework of the current legislative field and logistical capabilities without the involvement of government agencies," it said.

Moscow and Kyiv have carried out several exchanges of children for reunification with their families since Russia's full-scale invasion in February 2022.

Ukraine says over 19,500 children have been taken to Russia or Russian-occupied territory without the consent of family or guardians during the war, calling the abductions a war crime that meets the U.N. treaty definition of genocide.

Russia has said it has been evacuating people voluntarily and to protect vulnerable children from the war zone.

Kyiv has brought back 388 children so far, according to data published by Ukraine's Ministry of Reintegration.

In March 2023, the International Criminal Court issued warrants for the arrest of Lvova-Belova and President Vladimir Putin related to the abduction of Ukrainian children. Russia denounced the warrants as "outrageous and unacceptable". (Reporting by Oleksandr Kozhukhar; Writing by Lidia Kelly in Melbourne; Editing by Michael Perry and Buy Monetized YouTube Channels Timothy Heritage)