Russia has expelled two German diplomats in response to a spat with Berlin over a German court's ruling that Moscow had ordered the 2019 assassination of an ex-Chechen commander in a Berlin park.
"The German ambassador was informed that two diplomatic employees of the German embassy in Russia were declared 'persona non grata' as a symmetrical response," Russia's foreign ministry said in a statement.
It did not say when the German diplomats needed to leave Russia.
The ministry added that it had registered a "strong protest" with the German envoy over Berlin's expulsion of two Russian diplomats last week.
Last week, judges in Berlin sentenced Russian national Vadim Krasikov, alias Vadim Sokolov, to life in jail after convicting him of gunning down Georgian national Tornike Kavtarashvili, 40, in a Berlin park in 2019.
The murder was meant "as retaliation" for being a Kremlin opponent, a judge said.
"Divorced from reality"
Russia's foreign ministry said Monday that Moscow "categorically denies the unfounded and divorced from reality accusations" that it was involved.
Germany had already thrown out two Russian diplomats shortly after the murder in protest at Moscow's perceived lack of cooperation with the probe.
Russia denied any connection to the killing and responded with a tit-for-tat move.
Relations between Russia and Germany were already at a low.
On Sunday, German Economic Affairs and Climate Action Minister Robert Habeck warned Russia of "severe consequences" and threatened to halt the Nord Stream 2 gas pipeline, if Moscow were to attack Ukraine.
"Any new military action cannot remain without severe consequences," he told the Sunday edition of the Frankfurter Allgemeine Zeitung, referring to Russian troop deployment on the Ukrainian border.
Habeck warned that "nothing can be excluded," including blocking the pipeline from operation, if "there is a new violation of the territorial integrity" of Ukraine.
"In the event of further escalation this gas pipeline could not come into service," Foreign Minister Annalena Baerbock said earlier this week.