Social networking site Twitter is facing a £33 million lawsuit for refusing to divulge the identities of antisemitic users.

The site, which turns seven today, is being sued by the Union of French Jewish Students for ignoring a court ruling to turn over details of the users.

Twitter was told to work to help identify the authors of a string of abusive and antisemitic tweets, posted by various users under the tag #unbonjuif (#agoodjew) in October last year.

But the January court ruling was not binding, since the company does not have an office in France, and it has so far not complied.

Jonathan Hayoun, UEJF president, criticised the site for "playing the indifference card".

He said: "In protecting the anonymity of the author of these tweets it is making itself an accomplice and offering a highway for racists and antisemites."

The group has filed a claim with a Paris tribunal and is now seeking more than £33 million in damages, which it said would be donated to the Shoah Memorial fund.

A spokesman forTwitter criticised UEJF for being "more interested in these grand gestures than in finding an adequate international procedure to obtain the requested information".