• Special anti-cyber crime teams were investigating the attack

• There was no immediate comment from authorities in Moscow

• The hackers' email included an appeal for the release of WikiLeaks founder Julian Assange

Hackers stole millions of Bulgarians' personal and financial data and distributed it from a Russian-based email in an attack one minister linked to the purchase of new F-16 fighter jets from the United States, the government said on Tuesday.

The hackers accessed a system at Bulgaria's tax agency before sending an email from a Russian domain to some local media on Monday with links to data, officials said.

Picture shown is for illustrative purposes only.

Special anti-cyber crime teams were investigating the attack at the National Revenue Agency (NRA), which probably came from abroad and began at the end of June, they added.

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"Maybe this is the first case in Bulgaria which is successful and a lot of personal data has been stolen," Interior Minister Mladen Marinov told local bTV channel.

The cyber attack was likely motivated, he said, by Bulgaria's move to buy eight new Lockheed Martin F-16 fighters for $1.256 billion from the United States, its biggest military purchase since the end of communism.

But the finance minister did not concur with that theory.

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Once an obedient satellite of Moscow, the Balkan nation has joined the European Union and trans-atlantic NATO alliance since the turn of the century, and is replacing its ageing Soviet made MiG-29 planes with the F-16s.

A leading Bulgarian newspaper, 24 Chasa, said one file emailed by the hackers had more than 1.1 million identification numbers with income, social security and healthcare figures.

According to local web site Mediapool, the email came from an address with Russian mail provider Yandex.

There was no immediate comment from authorities in Moscow.

Finance Minister Vladislav Goranov said about 3% of the tax agency's database was affected, involving millions of records in the nation of 7 million people. The leaked information was not classified and did not endanger financial stability, he added.

Picture shown is for illustrative purposes only.

Goranov declined to link the attack to the F-16 purchase, noting it occurred before the government approved the deal.

Bulgaria's prime minister convened the national security council and all state institutions would be checked, Marinov said. Sofia also planned to seek help from the EU cyber security agency to fully audit its most sensitive systems.

Bulgarian media said the hackers' email included an appeal for the release of WikiLeaks founder Julian Assange. "Your government is mentally retarded. The state of your cyber-security is a parody," reports quoted it as saying.

Reuters