According to news reports, a password hacking scandal last Tuesday exposed login details of 90,000 Swedes, principally users of the popular Swedish blogging site Bloggtoppen.se.
Jimmy Holmlund, who operates the Bloggtoppen.se website, confirmed that the site had been hacked and has since been shut down.
"Someone apparently discovered a weakness in the code that lies behind the service," he told the TT news agency on Tuesday.
The account data was made public on the Twitter account of former Sweden Democrat MP William Petzll, who says his account was hijacked.
On Wednesday, the Swedish publication Aftonbladet reported that 57 other websites had also been hacked, putting login details of up to 180,000 Swedes at risk and making it one of the biggest security breaches ever reported in the country.
"I can't recall an attack in recent years that's been this big, said Joakim von Braun, a computer security expert who has worked with Swedish security service Spo and is now with Sveriges Radio (SR).
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