Ukraine estimates that nearly 30,000 children have been forcibly removed or deported from their homes by Russia.
Russia has returned five Ukrainian children to Kyiv with thousands still believed to be held by Moscow.
A report from Russian news agency TASS said that six children were reunited with their families after mediation at the Qatari embassy in Moscow.
Five of the children were sent to Ukraine, and one was returned to relatives in Russia, the outlet reported.
Russian children’s rights commissioner Maria Lvova-Belova said on Thursday: “In total, 64 children have already returned to Ukraine, six have [been] reunited with relatives in Russia.”
But, according to an estimate from the Ukrainian government, there are nearly 30,000 children who have been forcibly removed or deported from their homes.
In July last year, Ms Lvova-Belova claimed that 700,000 Ukrainian children had been brought to Russia for humanitarian reasons.
On 17 March 2023, the International Criminal Court issued arrest warrants for Vladimir Putin and Ms Lvova-Belova for the forced deportations of more than 16,000 Ukrainian children to Russia.
It comes after Russia said it would evacuate 9,000 children from the Belgorod region as Ukraine continues to shell the area.