MOSCOW, June 7 - RAPSI. Former FSB colonel Valery Mikhailov, sentenced to 18 years in prison for giving secret papers to the United States, cannot not be exchanged in return for Viktor Bout, sentenced in the United States for arms trafficking, RIA Novosti quotes from a high-ranking official in Russian security service.

The source commented on media allegations that the U.S. authorities are considering to ask for Mikhailov, considered by the CIA as one of the most successful agents in recent years, in exchange for "one of those Russian spies." The media has reported that Mikhailov could possibly be exchanged for a man unconnected with espionage - Bout sentenced to 25 years in prison for attempting to sell arms to Columbian guerrillas.

"This scenario is out of the question as Mikhailov caused great damage to Russia." The source ruled out that Bout could be exchanged for Mikhailov, but said he might be exchanged for someone else.