The UK government website went down on Saturday evening in what the hacking group described as a pre-planned denial-of-service, BBC News reports.
Anonymous launched the attack in protest of the government's extradition policy, which has allowed alleged cyber criminals in the UK to be sent for trial in the US.
The group also claimed it was a stand against the coalition's plans to monitor emails, web use and phone calls.
The Home Office website saw service disruptions between 9pm on Saturday night and 5am the following morning. Anonymous initially said that it would hit the site every Saturday, but the government claims that security measures are now in place to prevent repeat breaches.
"The Home Office website was the subject of on online protest last night. This is a public facing website and no sensitive information is held on it. There is no indication that the site was hacked and other Home Office systems were not affected," said a spokeswoman for the Home Office.
Anonymous targeted the Chinese government last week, defacing almost 500 of its websites in protest against censorship in the territory.
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