Jordanian terror suspect Abu Qatada was on Monday denied bail in his latest legal skirmish with British authorities, who have been trying to deport him for a decade.
The cleric has been in and out of British prisons since 2002 as he fights successive government attempts to send him to Jordan, where he has been convicted of terror charges in his absence.
To ministers' horror he was released from his latest stint in jail in November, but was arrested again in March for allegedly breaching his bail conditions.
A judge at Britain's Special Immigration Appeals Commission (SIAC) ruled on Monday that the preacher, once dubbed Osama bin Laden's right-hand man in Europe, should remain in custody.
"There is no doubt about the national security threat which the appellant presents," judge Stephen Irwin said.
"This appellant has in the past fled in order to avoid a court order, equipping himself with a false passport.
"He is highly intelligent, has a range of sympathetic and supportive contacts, and his risk to national security is undiminished.
"We reject the submission that he can, even now, be relied on to comply with his legal obligations and not to attempt to abscond."
In a surprise move earlier this month, Abu Qatada's lawyer told the court that the preacher would return to Jordan voluntarily if its parliament ratifies a treaty barring the use of evidence obtained by torture.
The issue is at the heart of Britain's long struggle to deport him to Jordan, where he faces a likely retrial over his alleged involvement in the planning of terrorist attacks.
Last year the European Court of Human Rights blocked his deportation due to fears that evidence obtained through torture would be used against him in the new trial.
SIAC ruled in November that he could be released despite posing a risk to national security.
However, the cleric was sent back to jail in March after a stash of mobile phones, computer memory sticks and other digital devices were found in his home in what Irwin said was a "significant" breach of his bail conditions.
Government lawyer Robin Tam said a USB stick found in the bedroom of Abu Qatada's eldest son had contained schoolwork but also "jihadist files" including references to Al-Qaeda.
Abu Qatada had admitted breaching bail conditions which prevent him from turning on mobile phones or possessing other communication devices at his taxpayer-funded home in London.
But he claimed that he did not use the phones, several of which belonged to his wife and children.
Abu Qatada's lawyer Daniel Friedman had told SIAC that ahead of his return to Jordan, his client "wants to spend time with his family to prepare to leave the country in a manner that safeguards the dignity and security of all involved".
The preacher "has been deprived of his liberty more than any other non-convicted person in British history", Friedman claimed.
Britain's interior ministry described Abu Qatada as "dangerous" and said it was pleased he had been denied bail.
"The best place for him is behind bars until he can be lawfully removed from the UK," the Home Office said in a Twitter post.
"The government remains committed to securing Abu Qatada's deportation as quickly as possible."