But the Kremlin also called for dialogue between authorities in Kiev and rebel leaders, as European Union ministers prepared to meet in Brussels to consider toughening sanctions on Russia.
"Moscow respects the expression of the people's will in Donetsk and Lugansk," the Kremlin said in a statement, calling for "the results to be implemented in a civilised manner, without any repeat of violence, through dialogue between representatives of Kiev, Donetsk and Lugansk."
It deepened a crisis that has brought Russia's relations with the West to their lowest point since the Cold War.
Separatist officials in Donetsk province said 89 per cent of voters backed breaking away from Ukraine in Sunday's vote.
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Roughly similar results were expected later Monday from Lugansk, the other separatist province that voted.
The United States and other Western countries have said they will not recognise the outcome of the vote, which comes some two months after Moscow annexed Ukraine's Crimea peninsula.
A group of pro-Kiev armed men were seen firing into a crowd of pro-Russian activists.
According to a freelance photographer working for AFP, two people were seen lying motionless on the ground but it was not clear if they were dead.