The head of Russia's lower chamber of parliament said on Friday that President Vladimir Putin had notified the house about plans to admit four regions of Ukraine into Russia - a technical step towards Russia's annexation of the territories.
State Duma Speaker Vyacheslav Volodin, a key Putin ally, said on the Duma's official Telegram channel that Putin had informed the parliament of official requests by the regions.
Russia had held what it called referendums in four partially-occupied areas of Ukraine - Donetsk, Luhansk, Kherson and Zaporizhzhia, and said they had produced overwhelming majorities in favour of joining Russia.
Western governments and Kyiv said the votes had been carried out under the coercion of occupation, were unrepresentative and breached international law.
Putin was due to preside over a signing ceremony with the Russian-installed heads of the four regions in the Kremlin later on Friday.