Slovakia said Monday it had expelled three Russian diplomats for "a serious crime," with local media reporting a possible link with the killing of a former Chechen rebel in a Berlin park last year.
"I can confirm that a decision has been taken to expel three employees of the embassy of the Russian Federation in Slovakia," Juraj Tomaga, head of the foreign ministry's press department, told AFP.
"According to information from the Slovak intelligence services, their activities were in conflict with the Vienna Convention on Diplomatic Relations," he said.
Tomaga also said that a visa issued by the Slovak consulate in St. Petersburg in Russia had been "misused and a serious crime was committed in the territory of another NATO and EU member state."
The spokesman did not provide further details.
Russia said it would respond to the expulsions "in a similar way," Russian media reported.
Slovakia's Dennik N daily said the Slovak consulate in St. Petersburg last year issued visas that allowed into the European Union a Russian citizen who was later suspected of killing Zelimkhan Khangoshvili, a Georgian national, in Berlin's Kleiner Tiergarten park.
German police arrested a suspect shortly after the shooting and prosecutors have accused Russia of ordering the murder — a claim dismissed as "unfounded" by Moscow.
Investigative website Bellingcat earlier named the suspect as Vadim Krasikov, saying he was a contract killer who grew up in Kazakhstan when it was part of the Soviet Union before moving to Siberia.