Sweden's military uncovered a man who had used forged credentials to work there for 18 years.

The man had worked at NATO headquarters and was even in contact with Russian security services, though Sweden's top military officer said no classified information was divulged.

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COPENHAGEN, Denmark (AP) — A man who duped the Swedish military for 18 years by using forged credentials and who even worked at NATO headquarters and was a contact for Russia's security services did not divulge any secret information that could harm Sweden's security, the country's top military commander said Thursday.

The Swedish man, who was not named, was detected as a fraud last year.

"There is nothing that indicates that classified information has been disseminated," Gen. Micael Byden, the head of Sweden's Armed Forces, told reporters, according to Sweden's news agency TT.

Byden on Thursday informed the Swedish Parliament's Defense Committee of an internal investigation into the case that has rocked the country. Sweden is not a member of NATO but has moved closer to the military alliance in recent years. Details of the probe have not been made public.

The fake officer was exposed after having joined Sweden's UN peacekeeping force in Mali as Chief of Staff with the rank of major.

According to Swedish daily Dagens Nyheter, which uncovered the story earlier this month, the man used forged certificates falsely showing that he had passed the Swedish Army Forces' officer training program and also falsely claiming to have a university degree in politics.

The man had worked with the Swedish army's intelligence and security service, the daily reported, adding he also had been a contact person for Russia's Federal Security Service (FSB), the main KGB successor agency. At NATO's military headquarters, or SHAPE, in Belgium, the fake officer worked on the now defunct Afghanistan Mission Network, where nations shared intelligence, surveillance and reconnaissance information.

The military chief told TT that "at least once, an employment decision has been made on unclear grounds."

There was no immediate comment from NATO on the man.