Two members of the animal rights group Speak could be sent to prison for refusing to provide a list of email addresses of its 700 supporters.

Robert Cogswell, left, and Mel Broughton have been summoned to appear at the High Court in London next Tuesday charged with contempt.Mr Cogswell said the contempt proceedings followed an order issued by Mr Justice Gibbs on October 19, banning Speak from naming the construction company it believed is building Oxford University's £18m animal research laboratory, in South Parks Road.

Speak had named the firm on its website, but has now removed the article containing the name. Mr Cogswell said: "We could get a massive legal costs order against us, which would bankrupt us or, technically, the offence is imprisonable.

"We don't want to go to prison but we're quite prepared to go to prison if we have to.

"The university is making a grave mistake if they think they can muzzle a legitimate campaign."

Mr Cogswell said the order proposed that Speak's email alert list should be given to the university, so that individual members could be contacted and asked not to disseminate the name of the company.

But he said Speak would not be releasing the list of 700 names because it considered it a "fishing expedition" by the university and an attempt to undermine the campaign.

A university spokesman said: "This matter is now in the hands of the courts, but members of Speak are aware that court orders exist, and that they may be liable to penalties if they breach the injunction protecting all those associated with the university from harassment and intimidation."