US first lady Melania Trump on Friday said she has been in talks with Russian President Vladimir Putin to repatriate children caught up in the Ukrainian war, and that some have been returned to their families, with more to be reunited soon.

"This remains an ongoing effort," she said in comments at the White House.

Eight children had been returned to their families within the last 24 hours, she said.

"President Putin and I have had an open channel of communication about the welfare of these children," she said. "For the past few months, both sides have participated in several back-channel meetings and calls."

Melania Trump urges Putin to help reunify Ukrainian children with their families

The first lady said her representative was working directly with Putin's team to secure the safe reunification of children with their families between Russia and Ukraine.

She added that Russia provided her with photos and biographies of the eight children who were reunited with their families this week, along with the services that the Kremlin claims to offer them.

"I hope peace can come soon. It can begin with our children," she stated. 

Ukraine has called the abductions of tens of thousands of its children taken to Russia or Russian-occupied territory without the consent of family or guardians a war crime that meets the UN treaty definition of genocide.

Previously, Moscow has said it has been protecting vulnerable children from a war zone.

"Russia continues to cooperate with the United States in various areas, including humanitarian ones. We appreciate Melania Trump's humanitarian leadership," said Russia's presidential envoy Kirill Dmitriev, who was involved in discussions.