Two British men wanted by the United States on terrorism charges launched a bid to block their extradition yesterday, saying they fear mistreatment by US authorities if they are handed over.

Lawyers for Babar Ahmad and Haroon Aswat told two of Britain's leading judges at the High Court the men feared they would be treated as "enemy combatants" by the United States and faced a risk of "fundamental injustice and discriminatory treatment".

Mr Aswat has been held in Britain since being arrested in Zambia a year ago. A criminal complaint filed in a US federal court accuses him of conspiring to set up a camp in Bly, Oregon, in 1999 and 2000 to train fighters for war in Afghanistan.

Mr Ahmad, 31, a computer expert from south London, has been held in jail in Britain on a US arrest warrant since August 2004. He is accused of running a website that raised funds for Muslim militants in Afghanistan and Chechnya.

The men's lawyer, Edward Fitzgerald, told the court the suspects feared they could be detained indefinitely under a military order applying to foreign citizens or tried and sentenced by a military commission as "enemy combatants" like those being held in the US Guantanamo prison camp in Cuba.

This would be a "flagrant denial of justice," he said. Under legislation introduced in 2003, the United States can seek extradition without having to present evidence to a British court.

Washington has promised the two British men will not be sent to Guantanamo or turned over to a third country, but Fitzgerald urged the High Court judges not to rely on US assurances that the men would be treated fairly.

Mr Ahmad's supporters, who have waged a vociferous campaign, argue he should face trial in Britain if he has charges to answer.

About 80 demonstrators gathered outside the central London court waving banners reading Isn't British justice good enough and No to US injustice.

Moazzam Begg, a British Muslim who was held at Guantanamo for almost three years before being released without charge, said it would be a "travesty of justice" to extradite Ahmad.

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