Russia says it has expelled a German diplomat and several Polish diplomats in response to the recent expulsions of Russian diplomats.
Russia's Foreign Ministry said on November 17 the German was expelled over the weekend in a retaliatory measure for what it described as an "unfriendly" step earlier by Berlin of expelling a Russian diplomat.
The ministry accused the Polish diplomats of activities inconsistent with their status, a phrase generally used for spying.
It confirmed reports that Warsaw had expelled several Russian diplomats, citing the same accusation.
"The Polish authorities indeed took such an unfriendly and absolutely groundless step," the ministry said in a statement.
"In connection with that, Russia has undertaken adequate measures in response and a number of Polish diplomats have already left the territory of our country for activities incompatible with their status," it added.
Polish Foreign Minister Grzegorz Schetyna was quoted as saying on November 17 that Warsaw considered Moscow's move a "symmetric response."
"For us, this affair is closed," he added.
The authorities did not give further details, but Polish media reported that four Polish diplomats were told on November 14 they had 48 hours to leave Russia, meaning they had presumably returned to Poland by November 16 evening.
Relations between Moscow and European Union member states have been strained by the crisis in Ukraine and by EU sanctions imposed after Russia annexed Crimea from Ukraine.
Russian authorities made espionage allegations against citizens of other nearby EU member states.
Russian television reported on November 16 that a former member of the Latvian parliament, Aleksejs Holostovs, had been expelled from Russia for spying.
Also an Estonian police officer detained since September has been charged with espionage, despite calls from Western leaders for his immediate release.