Map showing sepratist regions in Ukraine. AFP
The four regions are Donetsk, Kherson, Luhansk and Zaporizhzhia. The announcements of referendums starting Friday came after a close ally of Russian President Vladimir Putin said they were needed.
Former Russian President Dmitry Medvedev also said that folding Luhansk and Donetsk in eastern Ukraine into Russia itself would make their redrawn frontiers "irreversible'' and enable Moscow to use "any means'' to defend them.
Such votes would almost certainly go Moscow's way, but not be recognized by Western governments. The votes could set the stage for Moscow to escalate the conflict as Ukrainian forces battle with growing success to take back territory.
Denis Pushilin, the head of the Donetsk region, said that the "long-suffering people of the Donbas have earned the right to be part of the great country that they always considered their motherland.'' He added that the vote will help "restore historic justice that millions of the Russian people were waiting for.''