Italy has expelled two Russian officials involved in suspected spying, Foreign Minister Luigi Di Maio said on Wednesday (March 31) after summoning the Russian ambassador over the affair.
Italian police said earlier they had arrested an Italian navy captain and a Russian diplomat on suspicion of spying after the two were caught swapping documents for money at a clandestine meeting.
Di Maio said on Facebook that he had protested firmly to Russian ambassador Sergey Razov and informed him of the "immediate expulsion of two Russian officials involved in this extremely serious matter."
Razov had earlier been summoned by the foreign ministry.
NATO documents were among the files the navy captain passed to the Russian official, Ansa news agency said, raising potential security worries for other members of the Western military alliance.
The Kremlin said it hoped Russia and Italy would maintain positive and constructive ties despite the arrest of a Russian official in Rome in a spying case.
The Kremlin said it did not have any information about the reasons and circumstances for the detention.
The incident was the latest in a series of spying accusations in recent months against Russians in European countries. Bulgaria expelled Russian officials on suspicion of spying in March, and the Netherlands did so in December.
The arrests were ordered by Rome prosecutors following a long investigation carried out by the Italian intelligence with the support of the military, the Carabinieri police force said.
Police did not specify where the arrests had taken place. No further comment would be made until a magistrate approves the arrest, they said.