TWITTER has been forced to hand over the personal details of a British website user in a landmark court ruling, which could have major implications for freedom of speech on the internet.

South Tyneside Council in South Shields has successfully pursued legal action against a blogger known as Mr Monkey, who has, allegedly, levelled a stream of false accusations against its councillors and staff.

The local authority went to court in California, where the social network website is based, to get the blogger’s personal details revealed.

It is thought the move could have implications for the new world of online social media and for celebrities wishing to track down Twitter users who have broken privacy injunctions.

Last week, Manchester United footballer Ryan Giggs was identified by the Sunday Herald as the plaintiff in a gagging order, which prevented the reporting of his alleged affair with a reality TV model.

The newspaper defended its action by saying it was untenable for its readers not to know Mr Giggs’s identity when people could do so at the click of a computer mouse. Prime Minister David Cameron described the position as “unsustainable” and a Westminster inquiry has been launched to look at the complex issue of the internet, the courts, freedom of speech and privacy.

Mr Giggs had begun a move through the courts to try to unmask those Twitter users accused of revealing the details of his privacy injunction. However, the footballer brought his lawsuit at the High Court in London and not in California.

Last week, ahead of the G8 leaders’ summit, an “e-summit” was held to discuss the topical issues and was attended by Google’s Eric Schmidt and Facebook founder Mark Zuckerberg.

Tony Wang, Twitter’s new European head, made clear users of the network who broke privacy injunctions by posting comments on the website could be pursued in UK courts. He said people who did “bad things” had to defend their actions and he warned Twitter would give information to authorities if legally obliged to do so.

A spokesman for South Tyneside Council said it had “a duty of care” to protect its employees and legal action was being taken to identify those responsible for the blog.

Local councillor and businessman David Potts said: “We have a duty to look after our employees. It is not a case of politicians not wanting to be criticised. I don’t mind being criticised. I’ve got a thick skin. But this blog is perverted, sleazy, sick, filthy and is full of sordid lies.”

Ahmed Khan, another councillor suspected of being Mr Monkey, denied he was the blogger but confirmed last night he was informed by Twitter earlier this month his account details had been disclosed after a subpoena was lodged with a court. He said rather than being the culprit in the case, he was a victim.

“I don’t fully understand it but it all relates to my Twitter account and it not only breaches my human rights but it potentially breaches the human rights of anyone who has ever sent me a message on Twitter,” Mr Khan told the BBC.

“This is Orwellian. It is like something out of 1984,” he said.

The councillor admitted being critical of South Tyneside’s policies but added: “People who had the courage to come forward and expose possible wrong within South Tyneside Council will now not do so. Constituents who have used Twitter to engage with me, to air any problems or concerns they have, will also think twice before doing that.”

Mark Stephens, the media lawyer who represented Wiki-leaks founder Julian Assange, said he was unaware of any previous cases, adding: “The implications are that people who have had their name released can actually now go to California and begin proceedings.”

However, another media lawyer, Steve Kuncewicz, doubted the South Tyneside Council case would have much bearing on celebrities and injunctions because its action was in America not Britain.

“This is a big deal but it’s only significant in relation to US law and not ours. There’s no white flag being waved by Twitter just yet,” he added.

The US company declined to comment.