Twitter has been forced to hand over personal information belonging to a British politician after council leaders launched an international court case.
It is believed to be the first time the American social networking site has bowed to a court action brought by a British group complaining that they were libelled in messages.
The ruling by a court in California has prompted a row over privacy and freedom of speech.
The latest revelations could have huge implications for Twitter users who outed footballer Ryan Giggs for having an affair with Imogen Thomas.
The footballer used a Superinjunction to keep the affair under wraps but an estimated 75,000 users named Giggs as the Premier League player who had used the draconian ruling to hide his extramarital affair.
There was speculation that Giggs would never be able to get Twitter to hand over private account information, until now.
South Tyneside Council is believed to have spent hundreds of thousands of pounds on the case in the hope of unmasking the secret author of a blog who goes by the name of Mr Monkey.
Independent Councillor Ahmed Khan is suspected by council leaders as being the author, which has made a series of unfounded allegations against council leaders.
Mr Khan fiercely denies the accusations and said he was horrified when Twitter sent him an e-mail telling him they had handed over private information, including personal messages, he had sent from the social networking site.
'This is Orwellian. It is like something out of 1984,' said Mr Khan, 'If a council can take this kind of action against one of its own councillors simply because they don't like what I say, what hope is there for freedom of speech or privacy?'
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.
"This is Orwellian. It is like something out of 1984."
The Mr Monkey blog has made a number accusations against the council's Labour leader Iain Malcolm, as well as David Potts, the former Conservative leader who now serves as an Independent councillor, Labour councillor Anne Walsh and Rick O'Farrell, the council's head of enterprise and regeneration.
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Media lawyer Mark Stephens says he is unaware of anyone from the UK taking action like this before
They are all named on papers delivered by the council's lawyers to the Superior Court of California.
A spokesman for South Tyneside Council said: "This legal action was initiated by the council's previous chief executive and has continued with the full support of the council's current chief executive.
"The council has a duty of care to protect its employees and as this blog contains damaging claims about council officers, legal action is being taken to identify those responsible."
He said he had no knowledge of councillors attending court hearings in the US or whether Twitter had as yet handed over any confidential information.
"It is like something out of 1984," Khan told the Guardian. "If a council can take this kind of action against one of its own councillors simply because they don't like what I say, what hope is there for freedom of speech or privacy?"
Khan said the information Twitter handed over was "just a great long list of numbers". The subpeona ordered Twitter to hand over 30 pieces of information relating to several Twitter accounts, including @fatcouncillor and @ahmedkhan01.
"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.
"A number of whistleblowers have sent me private messages, exposing any wrongdoing in the council, and the authority knows this."
He added: "I was never even told they were taking this case to court in California. The first I heard was when Twitter contacted me. I had just 14 days to defend the case and I was expected to fly 6,000 miles and hire my own lawyer – all at my expense.
"Even if they unmask this blogger, what does the council hope to achieve ? The person or persons concerned is simply likely to declare bankruptcy and the council won't recover any money it has spent."
A spokesman for south Tyneside council said the legal action was brought by the authority's previous chief executive, but has "continued with the full support" of the current head.
He added: "The council has a duty of care to protect its employees and as this blog contains damaging claims about council officers, legal action is being taken to identify those responsible."
Twitter had not returned a request to comment at time of publication.