Ousted Ukrainian President Viktor Yanukovych asked Russia to send troops across the border.
Moscow's UN envoy Vitaly Churkin told a United nations Security Council meeting that Yanukovych wrote a letter to Russian President Vladimir Putin asking to send the troops to protect the civilians.
According to the BBC, at the UN in New York, Churkin showed the UNSC a copy of the letter Yanukovych had sent.
He said Yankovych had described Ukraine as on the brink of civil war, with civilians being persecuted simply for speaking Russian.
Churkin reiterated Moscow's view that Yanukovych is Ukraine's legitimate leader, not interim President Olexander Turchynov.
Western ambassadors refused to accept Russia's justification, continuing to accuse Moscow of violating international law, the report added.
