The Foreign Ministry summoned the Russian ambassador, Sergey Razov, after the sting operation late Tuesday caught the two in what police said was a “clandestine operation” to exchange the goods. 

Italy's Carabinieri paramilitary police said in a statement that the Italian official, who is a frigate captain, had been arrested. The Russian, a member of the Russian armed forces stationed at Moscow's embassy to Italy, has been detained but his status is “under consideration” given his diplomatic position, the statement said. 

Italy's special operations forces in Rome staged the operation “during a clandestine operation between the two, surprising them red-handed immediately after the handing over of classified documents by the Italian official in exchange for a sum of money,” the statement said. 

The Carabinieri said both were accused of “serious crimes concerning espionage and state security.” 

The Russian Embassy in Rome confirmed the detention of a diplomat who was part of the military attache's office but wouldn't comment on the incident. 

“In any case, we hope that it wouldn't affect bilateral ties,” it said in a statement.