KIEV (REUTERS) - The Crimean assembly's vote to join Russia on Thursday was coordinated with the two houses of Russian parliament, a Ukrainian foreign ministry official said on Thursday.

"All that is happening now - the decision by the Crimean Supreme Council and statements by the Federation Council and State Duma - are evidence that this is coordinated action,"Interfax news agency quoted Yevhen Perebiynis as saying.

"Now the masks are off and we can see for what purpose it all began." Crimea's parliament voted to join Russia on Thursday and its Moscow-backed government set a referendum for March 16.