Lawyers for an Algerian man, wanted in connection with a series of Paris train bombings in 1995, say new moves to extradite him are "legally flawed".
Eight people died in the 1995 attack on Saint Michel Metro station
Rachid Ramda, the UK's longest-serving extradition prisoner, is challenging a Home Office ruling he must be removed.
Mr Ramda is accused of conspiring in an explosion at Paris Metro station which killed eight people and of organising and financing several other bombings.
The 10-year extradition battle has caused anger in France.
Mr Ramda, 35, faces 23 charges of financing and organising a bombing campaign in France between August and November 1995.
On a separate extradition request, he is accused of being a conspirator in the bombing of the Saint Michel Metro station on 25 July 1995, in which eight people were killed and 87 injured.
He is also believed to be a financier of Algeria's outlawed Armed Islamic Group (GIA).
The GIA, which fights the government in Algeria, is thought to be responsible for the 1995 bombing campaign.
In April, Home Secretary Charles Clarke made a fresh extradition order on the basis that Mr Ramda, who is being held at London's Belmarsh prison, would receive a fair trial.
But on Friday, Mr Ramda's QC Edward Fitzgerald told two High Court judges Mr Clarke's decision was "legally flawed" and that "bad faith" had been shown by the French government.
In 2002, two High Court judges quashed an extradition order, signed by the then Home Secretary David Blunkett, and ordered the case be reconsidered.
Then the judges had expressed concern that evidence against Mr Ramda came from co-defendant Boualem Bensaid, said by his lawyers to have been tortured during interrogation while in French custody.
In the latest hearing, Mr Fitzgerald told Lord Justice Keen and Mr Justice Poole they should quash the new extradition order because Mr Clarke was wrong to conclude the defendant could raise the issue of Bensaid's treatment in his own trial.
The lawyer also said Mr Clarke had failed to consider whether there was a real risk Mr Ramda himself would suffer inhuman treatment if extradited, which would be in breach of the European Convention on Human Rights.
In all, there have been nine separate legal proceedings to extradite Mr Ramda.
A woman who was seriously injured in the French bombings has spoken of her frustration at the delay.
Francoise Rudetzki contrasted the case with the UK request for the extradition of 21 July London bombing suspect Hussain Osman who was returned from Italy at the end of September.
"What would the British think 10 years from now if he was still in Italy?" she asked recently.
Supporters of a campaign to block Mr Ramda's extradition say he could eventually deported from France to Algeria where, they claim, he could face execution.