Micro-blogging site Twitter has apparently refused to help Big Brother star Imogen Thomas  track down users that have been harassing her on the micro-blogging site.

Thomas went to the police after an unidentified Twitter user threatened her and her family via the the site. One message sent via Twitter read: "I wanna hear u scream and fear when u see what I do to you and your family".

Thomas' media advisor Max Clifford claims the micro-blogging site has refused to co-operate with the police in tracking down the users.

"Scotland Yard spoke to Imogen this morning. They are taking it very seriously," Clifford said yesterday.

"The officer told her that Twitter was not co-operating but reassured her that the police have their ways of finding these people and are going after them."

It is thought the negtaive attention has been directed at Thomas after it was alleged she had an affair with a married Premiership footballer. However, the footballer obtained a super injunction which prevented details of the extra-marital affair being leaked to the press.

Ryan Giggs was later named as the football behind the injunction by Liberal Democrat MP John Hemming, who used parliamentary privilege to name him in parliament.

Giggs has also threatened to sue thousands of web users, including former Britain's got Talent judge Piers Morgan and DJ Boy George, after they breeched the terms of the superinjunction by naming him on the site.

Twitter's head of European operations was also dragged into the row this week and revealed the micro-blogging service will provide authorities with details of users who have breached super injunctions if "legally required".

"If we're legally required to turn over user information, to the extent that we can, we want to notify the user involved, let them know and let them exercise their rights under their own jurisdiction," said Tony Wang, head of European operations at Twitter.

Twitter has yet to respond to a request for comment on the matter.