Italy announced it had expelled two Russian diplomats and arrested an Italian navy captain on Tuesday on suspicion of their involvement in espionage.
According to media reports, the diplomats were expelled on Wednesday.
Italian police say the captain and an official of the Russian embassy were arrested in a parking lot in Rome. They are accused of "serious crimes related to espionage and the security of the country".
Reuters news agency, citing an Italian police official, said the captain's name was Walter Biot and he was accused of leaking information in exchange for $ 5,900.
The Italian news agency ANSA reported that some of the seized documents were NATO documents.
Italian police said the arrests were the result of a lengthy investigation by national security officials and the military.
Following the arrests, Italy expelled two Russian officials suspected of being involved in the incident.
Italian Foreign Minister Luigi Di Maio described the incident as "extremely serious", Reuters reported.
"During the meeting of the Russian ambassador at the Italian Foreign Ministry, we announced the strong protest of the Italian government and announced the immediate expulsion of two Russian officials involved in this extremely serious issue," the minister wrote in a Facebook post.
In occasione della convocazione al Ministero degli Affari Esteri e della Cooperazione Internazionale dell’ambasciatore...
Posted by Luigi Di Maio on Wednesday, March 31, 2021
According to Reuters, Mr. Biot, 54, was working in the Italian Ministry of Defense in a department in charge of developing national security policy and maintaining relations with the country's allies.