The Anonymous cyber-hacking group has claimed responsibility for a series of attempted attacks on British government websites, in support of WikiLeaks founder Julian Assange.

Anonymous said on Twitter it had launched the attacks in support of Mr Assange, who is holed up in the London embassy of Ecuador, which has granted him asylum as he bids to avoid extradition to Sweden over sex crime allegations.

A Ministry of Justice spokeswoman said its website “has been experiencing some disruption”.

“This is a public information website and no sensitive data is held on it. No other Ministry of Justice systems have been affected,” she said.

A similar attack was made on the website of British Prime Minister David Cameron, but it failed to bring the site down, a Downing Street spokesman said.

The Home Office, or interior ministry, denied its website was “hacked”.

“It was targeted by protesters on Monday night but only experienced very minor interruption to the service,” a spokeswoman said.

“We had measures in place to protect the site and no other Home Office systems were affected.”

Mr Assange and his supporters claim that if extradited to Sweden, he would then be extradited to the United States, which WikiLeaks enraged by releasing tens of thousands of classified documents about the wars in Iraq and Afghanistan.