WASHINGTON: The United States has expelled a man who was reported to be a 12th Russian agent in the espionage ring that end last week with a Cold War-style spy swap, a US official said Tuesday.

Alexey Karetnikov was "ordered removed from the United States by an immigration judge," said Matt Chandler, a spokesman for the Department of Homeland Security.

The statement followed a Wall Street Journal report that said a 23-year-old Russian man had been detained in the United States as part of the decade-long federal probe into the spy ring.

The removal, which Chandler said was ordered Monday but declined to say when it was carried out, came after an agreement where Karetnikov "admitted that he was present in the United States in violation of immigration law."

Karetnikov voluntarily agreed to his deportation instead of facing court proceedings, said the official, who added the man would face criminal and civil penalties if he returned to the United States "without express US Government permission."

The arrest of 10 agents, who pleaded guilty to working as deep cover "sleepers" for up to a decade, were swiftly sent back to Russia last Friday in exchange for four spies convicted in Russia, in a move that appeared aimed at limiting any damage to improving ties between the superpowers.

An 11th agent was arrested in Cyprus but later vanished after posting bail.

BDST:0918 HRS, July 14, 2010