Italy expels two Russian officials after Italian foreign minister Luigi Di Maio summons Russian ambassador.

An Italian navy captain and a Russian diplomat have been arrested on charges of "serious crimes related to spying and state security" following a "clandestine meeting" between the two late last night, police said.

It is alleged that the Italian officer, a frigate captain, handed over classified documents containing state secrets to the Russian official, who works at the Russian embassy to Italy, in exchange for money.

The carabinieri military police swooped during the meeting, arresting the two immediately after the "transfer of a document by the Italian officer in exchange for a sum of money," according to a statement from the police.

Russia's ambassador Sergey Razov was summoned this morning by Italy's foreign minister Luigi Di Maio who informed him of the “immediate expulsion of two Russian officials involved in this extremely serious matter.”

The suspects have not been identified and the police have not revealed the location of the arrests, which followed a lengthy investigation by Italian intelligence officials, Reuters reports.

NATO documents were among the top-secret files the Italian naval officer gave to the Russian official, potentially compromising the national security of other countries, reports Italian news agency ANSA.

Earlier today the Russian embassy issued a statement confirming the arrest of "an official from the office of the military attaché" but said that it considered it "inappropriate to comment" on the case.

The embassy also said that it hoped the incident would not affect bilateral relations between Russia and Italy.

Italian newspaper La Repubblica has described the case as "the most serious episode since the Cold War."

Photo credit: Luca Lorenzelli / Shutterstock.com

Abbiamo trasmesso all’ambasciatore russo in Italia la ferma protesta del governo italiano e notificato l’immediata espulsione dei due funzionari russi coinvolti in questa gravissima vicenda. pic.twitter.com/B8Q2OpZfBt

— Luigi Di Maio (@luigidimaio) March 31, 2021