The FBI's investigation into a Russian spy ring that operated in the United States has resulted in another Russian being detained, and he soon will be deported, a U.S. law enforcement official said on Tuesday.

The official said the 23-year-old Russian, who was not identified, had been closely monitored by FBI agents since his arrival in the United States in October of last year.

He was caught up in the investigation that resulted in last week's guilty pleas in federal court in New York of 10 individuals who admitted being agents for Russia while living undercover in the United States.

In one of the biggest spy swaps since the end of the Cold War more than two decades ago, the 10 were exchanged in Vienna on Friday for four individuals who had been imprisoned in Russia for contacts with Western intelligence agencies.

In addition to the 10 convicted last week, U.S. prosecutors have charged an 11th person as part of the spy ring. He went missing last month after his release on bail in Cyprus and his whereabouts remain unknown.

The U.S. law enforcement official said there was no evidence the latest Russian man, being detained pending his deportation, possessed or passed classified information.

He has not been charged with any criminal violations.

"This guy was not a big fish," the official said, declining to be further identified because of the case's sensitive nature.

The Russian was in federal custody and will be deported "very soon," the official said. The man's location was not disclosed.

The spy swap helped to resolve a scandal that threatened to strain U.S.-Russian relations. Such swaps are not unprecedented but were more a fixture of the Cold War.

The official declined to comment on whether the Russian was part of the spy swap. He said the decision had been made by the U.S. government to deport him to Russia.
 

Reuters