Several Swedish official websites were knocked offline Monday, although no one has claimed responsibility for the attacks.

"I can confirm that the government site had problems today, but for security reasons, I cannot say more," Anna Dahlen, a government spokeswoman, told AFP adding that she did not know when the site would be back online.

Among websites hit were -- which gives general information about the country, and the armed forces' portal.

Patrik Braennstroem, webhost of, said it "came under a DDoS (distributed denial of service) attack."

He believes that other official sites were "undoubtedly" victims of the same attack.

As of Monday evening, no one had claimed responsibility for the incident.

"There were claims last night about being hit, but we really can't confirm it at this stage," a tweet by the Swedish branch of Anonymous hackers said, referring to the government's website.

Anonymous "usually claims its attacks and does it noisily," Internet community expert Marcin de Kaminski told AFP.

Anonymous has carried out several cyberattacks against government websites, including those ofPoland and Greece.