Almost 1.1 million people have been taken to Russia from war-hit areas of Ukraine since Moscow's invasion of its neighbour began in February.
Among those taken to Russia are around 200,000 children, Russian military chief Mikhail Mizintsev said, as cited by Interfax news agency.
On Monday alone 11,500 people, including 1,850 children, were brought to Russia from Ukraine, he said.
Russia frames this as an evacuation operation to bring people to safety from the fighting on the ground and alleged violence from Ukraine's leadership in Kiev.
Ukraine sees it as the forced deportation of its citizens from Russian-occupied territories in the east and south. According to Kiev, the Russian army does not allow people to flee Ukrainian-controlled territory.
Ukraine's National Security and Defence Council has accused Russia of abducting Ukrainian children and using them for propaganda purposes.
Moscow brought what it says are refugees from the Donetsk and Luhansk separatist regions in eastern Ukraine even before the Russian invasion of Ukraine on February 24.
Luhansk and Donetsk, known collectively as the Donbass, are mostly controlled by pro-Russian separatists.
Shortly before the invasion, Russian President Vladimir Putin said he recognized the self-declared republics as independent of Kiev.