VIENNA — Austria on Friday ordered four Russian diplomats to leave the country after accusing them of espionage, an Austrian official said.

Austria — and particularly Vienna, its capital — has long been considered a hotbed for spying because of lenient espionage laws and a high concentration of diplomats, given the many international organizations based in the city.

The Austrian official, who spoke on condition of anonymity to discuss the matter, said the expulsions were linked to espionage and that the diplomats were told to leave in the coming days.

Austria’s Foreign Ministry said that three of the four were diplomats at the Russian Embassy in Vienna while the fourth was based at Moscow’s mission to the Organization for Security and Cooperation in Europe.

The ministry, in a brief statement, said the Russian diplomats had “engaged in activities incompatible with their diplomatic status” and had therefore been declared personae non gratae. The ministry did not provide further details about the diplomats or their alleged activities.

Russia’s Deputy Foreign Minister Dmitry Lyubinsky told the state-run Russian news agency TASS that “a reaction is unavoidable.”

The move brings the number of expelled Russian diplomats since 2020 to 18.

In May, Austria expelled three Russian Embassy employees who were suspected of espionage by using antennas on Russian diplomatic buildings, according to the Austrian Foreign Ministry. The installations allowed Russia to intercept data transmitted by international organizations based in Vienna via satellite internet, Austria’s public broadcaster ORF reported at the time.

European nations and Russia have expelled each other’s diplomats on several occasions since Moscow’s full-scale invasion of Ukraine. Austria has given aid to Ukraine but not military equipment since it has a policy of military neutrality.

Foreign Minister Beate Meinl-Reisinger and her liberal Neos party have frequently called for taking a tougher stance on Russian espionage in Austria, including calling for an overhaul of Austria’s espionage legislation.

The legislation now in place punishes espionage by foreign services only if it targets Austrian interests.

An overhaul of the legislation is still being worked out and negotiated by the Austrian government, which aims to expand the punishment for espionage to include actions directed not only against Austria itself but also against international organizations.

Austria is a European Union member that has a policy of military neutrality.

Vienna is host to several U.N. agencies, including the International Atomic Energy Agency and the U.N. Office on Drugs and Crime, as well as other international groups such as the Organization for Security and Cooperation in Europe and OPEC.