More than 527,000 passports have been issued by Russia in the occupied parts of Eastern Ukraine in the past two years.
Press service of the Russian Interior Ministry made the relevant announcement revealing the data on May 2.
Russian President Vladimir Putin on April 2019 issued an order for a simplified and expedited citizenship process for residents of those areas.
Moscow's policy of handing out citizenship in Ukraine has come under intense international criticism as a bid to further destabilize the area, where more than 13,000 people have been killed since the fighting started in April 2014.
Ukraine has condemned the Russian naturalization of Ukrainian citizens as part of a hybrid-warfare campaign being waged by Moscow and a violation of Ukraine's sovereignty.
Russia has provided military, economic, and political support to the separatists in parts of Ukraine's Luhansk and Donetsk regions. Despite overwhelming evidence to the contrary, Moscow maintains it is not involved in Ukraine's domestic affairs.
The developments come at a time of heightened tensions between Russia and Ukraine in recent weeks, when Russia launched a major military buildup along its border with Ukraine and in the Black Sea Ukrainian region of Crimea, which was illegally occupied by Moscow in 2014.
Also, on March 20, a Russian presidential decree came into force banning non-Russian citizens from owning land in most of Crimea.
Earlier, Secretary of the National Security and Defense Council of Ukraine (NSDC) Oleksiy Danilov expressed his conviction that Ukrainians who have Ausweises (an allusion to ID documents issued by Nazi Germany's authorities to local residents during the German occupation of Ukraine in 1941-1944), illegal Russian passports, in the temporarily occupied territories of Donbas and Crimea will get rid of them when Ukraine regains these territories.