Russia has expelled a number of Polish diplomats accusing them of activities "incompatible with their status" in response to expulsions of Russian diplomats by Warsaw, the foreign ministry has said.
"The Polish authorities indeed took such an unfriendly and absolutely groundless step," the ministry said on Monday, confirming Polish media reports that several Russian officials had been expelled by Warsaw earlier.
"The Russian side took appropriate measures and a number of Polish diplomats have already left the territory of our country for activities incompatible with their status," the Russian foreign ministry said in a statement, using diplomatic language that generally refers to espionage.
The statement did not give details about the expelled officials.
The diplomatic row came as Russia has made espionage allegations against citizens of several other nearby NATO member countries, heightening tensions as Moscow finds itself in increasing international isolation over its actions in Ukraine.
Russian television reported on Sunday that a former member of the Latvian parliament, Aleksejs Holostovs, had been expelled from Russia for spying.
Russia has also charged an Estonian police officer with espionage and has held him in detention since September despite calls from Western leaders for his immediate release.