RIP BTC-e exchange

A Russian man suspected of being the anonymous mastermind behind one of the world's oldest crypto-currency exchanges and of laundering at least $4 billion has been arrested in Greece, police and sources said on Wednesday.

Police sources identified him as Alexander Vinnik, 38, who was arrested after a tip-off in a small beachside village in northern Greece on a U.S. warrant. Police said the United States would seek to extradite him.

Two sources close to the BTC-e virtual currency exchange, who declined to be identified while the case was open, said Vinnik was a key person behind the platform, which has been offline since reporting "technical problems" late on Tuesday.

"An internationally sought 'mastermind' of a crime organization has been arrested" Greek police said in a statement. "Since 2011 the 38-year-old has been running a criminal organization which administers one of the most important websites of electronic crime in the world."

Police said "at least" $4 billion in cash had been laundered through a bitcoin platform since 2011 - the year BTC-e was founded - with 7 million bitcoins deposited, and 5.5 million bitcoins in withdrawals.