Russia's Federal Security Service, or FSB, said Ryan Fogle, the third secretary in the political section at the U.S. Embassy in Moscow, was detained Monday night after he allegedly tried to recruit a member of the Russian intelligence services, The Wall Street Journal reported.
The Russian Foreign Ministry said Fogle has been declared persona non grata and demanded his immediate departure from Russia.
"The U.S. intelligence community recently has made repeated attempts to recruit employees of Russia's law-enforcement bodies and special agencies, which have been recorded and monitored by [Russia's] counterespionage forces," the FSB said in a statement.
The Wall Street Journal said the CIA and the U.S. Embassy in Moscow have declined comment.
The recruitment note allegedly found in Fogle's possession was released by the FSB and published on the website of the Russian TV channel RT. The New York Times said the letter offered $100,000 as a "down payment" for the Russian agent to "discuss your experience, expertise and cooperation."
FSB media officials said the letter was among a number of items confiscated from the agent, including two wigs, three pairs of glasses and several stacks of 500-euro notes.
The letter said: "This is a down payment from someone who is very impressed with your professionalism and who would greatly appreciate your cooperation in the future. Your security means a lot to us. This is why we chose this way of contacting you."
It was signed, "your friends."
Russian officials said Fogle had specialized technical equipment, instructions for the Russian citizen being recruited, a large quantity of cash and the means to change the person's appearance.
Fogle was taken to the FSB receiving office where he has been questioned and turned over to U.S. Embassy representatives, RIA Novosti said.