The Irish Government has ordered a Russian diplomat to leave the country after a police investigation determined that Russian intelligence had stolen the identities of Irish citizens to produce fake passports.
The Russian diplomat is believed to be Alexander Smirnov, a senior official in the embassy's consular section.
Smirnov has been given two weeks to leave the country after the Russian ambassador Mikhail Timoshkin was informed of the Irish governments decision.
The response from the Russian embassy was almost immediate. Russian deputy foreign minister Vladimir Titov hit out at what he called the "groundless and unfriendly act" and said it would not take place without a corresponding reaction.
Senior Irish sources told the press on Wednesday that they were unaware of plans by the Russian authorities to expel any Irish official serving in the Irish Embassy in Moscow.
Russia traditionally reacts to the expulsion of its representatives by making a similar move once the expelled diplomat returns to Moscow.