Austrian authorities have questioned a recently retired military officer under suspicion of spying for Russia for almost 20 years, Chancellor Sebastian Kurz has said.
Foreign Minister Karin Kneissl has summoned the Russian charge d'affaires over the matter and canceled an upcoming trip to Russia scheduled for December 2-3, Kurz added.
"We demand transparent information from Russia," Kurz said on November 9, adding that the Russian diplomat currently in charge at the embassy in Vienna was summoned to the Austrian Foreign Ministry.
"If the suspicion is confirmed, such cases, regardless of whether they take place in the Netherlands or in Austria, do not improve relations between Russia and the European Union," he said.
Kurz was referring to the expulsion of four Russian agents by the Netherlands in April for allegedly planning a cyberattack on the world's chemical-weapons watchdog in The Hague.
"Russian spying in Europe is unacceptable and to be condemned," Kurz added.
In response, Russia's Foreign Ministry summoned Austria's ambassador on November 9 to demand an explanation about the accusations, Russian news agencies reported.
Later in a statement on its website, the Russian Foreign Ministry said the allegations were harming hitherto positive bilateral relations.
The ministry said the allegations were based on suspicions rather than actual evidence and that it had expressed its protest to Austria's envoy when it summoned him earlier in the day.
Austrian Defense Minister Mario Kunasek told the news conference that the case came to light "a few weeks ago" as a result of information from another European intelligence agency.
Kurz said Austria was not going to withdraw its envoy from Moscow yet or expel Russian diplomats.
"We will discuss our further steps with European partners as soon as we receive more accurate information. In such a situation it is necessary to make gradual steps," Kurz said.
Austria is one of the few European countries that maintains close diplomatic contacts with Moscow despite Russia's actions in Ukraine, and even after the poisoning of ex-Russian spy Sergei Skripal and his daughter in Britain, which London has blamed on Russia.
Austrian Foreign Minister Karin Kneissl said she canceled her visit to Russia scheduled for December 2-3 due to the espionage case.
Vienna, home to multiple international organizations such as the IAEA, OSCE and a branch of the United Nations, is known as a European espionage hub.
The city also used to be a gateway to communist countries during the Cold War because of its proximity to Eastern Europe.