Amid the fallout from an espionage scandal that continues to rock Austria’s intelligence establishment, the country’s foreign minister, Karin Kneissl, has cancelled a planned visit to Moscow after the BVT and HNA – Vienna’s domestic and military intelligence services – revealed that a retired high-ranking officer in the Austrian Armed Forces had spied for Russia for nearly two decades.

Austrian investigators are scrambling to uncover the extent of the damage caused by the case, but have said that the individual in question, a retired colonel, began working as a source for Russian intelligence in the late 1990s and continued to do so until earlier this year.

According to Austrian Defence Minister Mario Kunasek, the case was uncovered by the country’s own internal intelligence services “a few weeks ago” after being tipped off by “a second European intelligence agency”.

The defence ministry and Austria’s security services believe the 70-year-old retired army colonel passed information on to the GRU – the Russian Federation’s military intelligence service – that “ranged from unimportant things to more sensitive information,” but that he was not in a position to reveal high-level classified data.

The suspect, whose identity has yet to be revealed, is believed to have passed on information from NATO seminars and courses that he had attended, as well as information available on the army’s intranet system. Though Austria is one of the few Western European countries that is not a member of the North Atlantic Alliance, it’s military cooperates closely with NATO members as an associated partner.

The scandal comes at an awkward time in relations between Moscow and Vienna. Austria, which was occupied by Soviet forces at the end of World War II and was seen as a gateway to the Eastern Bloc during the Cold War, is considered one of the few pro-Kremlin EU countries that have repeatedly opposed Europe’s economic sanctions against Russia for its ongoing military aggression against Ukraine.

Austria infuriated its Western partners earlier this year when its right-wing Chancellor Sebastian Kurz refused to join the United Kingdom and other European allies in expelling Russian diplomats following the March poisoning of ex-spy Sergei Skripal and his daughter Yulia at their adopted home in the UK city of Salisbury.

Kneissl was due in Moscow for bilateral talks with her counterpart, Sergey Lavrov, on December 2-3, but has now had to scrap those plans in the wake of the spy scandal. The situation is particularly awkward for Kneissl after being at the centre of an international controversy in August when she personally invited Russian President Vladimir Putin to her wedding and being photographed enthusiastically dancing a polka with him.

Kurz, a key member of the wave of nationalist politicians that have recently emerged as a force to be reckoned with in the EU and who has also publically stated his admiration for Putin, angrily responded to the case by stating that his government “Demands immediate transparent information from Russia,” adding, “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. We will discuss our further steps with European partners as soon as we receive more accurate information. In this sort of situation, it is necessary to take gradual steps.”

Austria has already summoned Russia’s ambassador in Vienna and demanded an explanation, a move that Moscow greeted with indignation. In a statement shortly after news broke about the spy scandal, Lavrov accused the Austrians of “treating Russia unfairly” through “unsubstantiated accusations”.