Radical cleric Abu Qatada is expected to be deported to Jordan next week, the Jordanian interior minister has said.
Abu Qatada arrived in Britain seeking political asylum in 1993
He is one of 10 foreign nationals, said to be a threat to UK security, arrested on Thursday pending deportation.
The cleric and at least two others had previously been held at Belmarsh Prison without charge. Their detentions were ordered by the home secretary.
In his absence, Abu Qatada has been sentenced by a court in Jordan to life in prison over a series of explosions.
He claimed asylum in the UK in 1993 after fleeing Jordan where he faced accusations of inciting terrorist acts.
He was convicted in absentia in 2000 on charges of conspiring to attack US and Israeli tourists during Jordan's millennium celebrations.
The indictment said his role was primarily to finance the plot.
His arrest and pending deportation follows a UK deal with Jordan that deportees would not be persecuted.
But human rights groups say their safety after deportation is not guaranteed.
And Gareth Peirce, who represents seven of the 10 detainees, said some of the men were at serious risk in prison.
She said five were on suicide watch, and that three of those had been badly affected by previous detention without trial.
She said some of the 10 were held in a high-security unit that had been declared unfit for human habitation. The Prison Service denies this.
The detainees are being held at Full Sutton Prison, near York, and Long Lartin Prison, in Worcestershire.
They were arrested in London, Luton, Leicestershire and the West Midlands.
Also on Thursday, Islamic preacher Omar Bakri Mohammed was arrested in Beirut, Lebanon.
On Friday, the Home Office announced he was to be excluded from the UK as his presence was "not conducive to the public good".
He was later freed by the authorities in Lebanon a day after he was arrested at Syria's request.
Right to appeal
Keith Best, chief executive of the Immigration Advisory Service, said the 10 men facing deportation could have lengthy rights of appeal to the Special Immigration Appeals Commission (Siac).
He said: "The process can drag on for months if not years."
RADICAL CLERIC ABU QATADA
Given refugee status in 1994 after arriving in UK on fake passport
Detained in Belmarsh jail in 2002 under laws introduced after 9/11 attacks
Linked to al-Qaeda by a British judge
Released under control order in March 2005
After Siac has made its decision, the detainees can lodge further appeals to the Court of Appeal, the House of Lords and, eventually, to the European Court of Human Rights at Strasbourg.
Under the Human Rights Act, the UK cannot deport anyone to a country where they may face persecution.
Some of those arrested come from Lebanon and Algeria, as well as Jordan, all of which have been criticised for poor human rights records.
The government has now reached agreement with Jordan that deportees will not be persecuted, and is in negotiation with 10 other countries, including Lebanon and Algeria.