The three diplomats are stationed at Russia’s embassy in Bratislava. They are believed to be intelligence officers operating under diplomatic cover. A spokesman from the Slovak Foreign Ministry issued a statement on Monday, citing “information from the Slovak intelligence services”, according to which the three Russians engaged in “activities [that] were in contradiction with the Vienna convention on diplomatic relations”. Additionally, said the statement, Slovak authorities had uncovered “an abuse of visas issued at the Slovak general consulate in St. Petersburgh, and in this connection a serious crime was committed on the territory of another European Union and North Atlantic Treaty Organization member state”.

The statement did not elaborate on the specifics of the “serious crime”, but Slovak media report that it refers to the killing last August of Zelimkhan Khangoshvili, a leading figure in the Second Chechen War, which pitted the Russian military against groups of Muslim fighters in the North Caucasus between 1999 and 2009. Khangoshvili, a Muslim born in Georgia, was a bodyguard of Aslan Maskhadov, the self-described leader of the Muslim separatists in the Northern Caucasus. In 2015, Khangoshvili sought political asylum in Germany after two men tried to kill him in Tbilisi. The German authorities initially placed him on a terrorism watch list, but removed him after he began to collaborate with German counterterrorist agencies and participate in programs designed to de-radicalize Muslim youth. He was shot in broad daylight in Berlin by a man wearing a wig and carrying a pistol fitted with a silencer. Officials from the Berlin prosecutor’s office said at the time there were “indications the deed was pre-planned and may have political motives behind it”. It is now believed that at least one of the men suspected of involvement in planning Khangoshvili’s killing had traveled from Russia to the European Union on a visa issued by the Slovakian consulate in St. Petersburgh.

The three Russian diplomats have reportedly been told that they have until this coming Sunday to leave Slovakia. The Russian embassy in Bratislava said it would not comment on the expulsions. Kremlin officials have strongly denied that the Russian government had any ties to the killing of Khangoshvili. Moscow has vowed to expel an equal number of Slovak diplomats from the Russian capital in the coming days.