Hundreds of Ukrainian children have been taken from orphanages and children’s homes to Russia, the ICC's chief prosecutor Karim Khan said in a statement on Friday.
Khan's statement came after the ICC issued arrest warrants for President Vladimir Putin and Maria Lvova-Belova, Russia's Commissioner for Children's Rights.
"Many of these children, we allege, have since been given up for adoption in the Russian Federation," he said.
Khan said a Russian law change has made it easier for the children to be adopted by Russian families while at the time of the deportations, Ukrainian children were protected persons under the Fourth Geneva Convention.
In his statement, Khan called today's arrest warrants "a first concrete step" while other Ukraine investigations are ongoing.
(Reporting by Charlotte Van Campenhout; Editing by Hugh Lawson)