Mr al-Rawi has lived in the UK for nearly 20 years

Bisher al-Rawi, an Iraqi national, was held at the US detention camp in Cuba on suspicion of links to terrorism while on a trip to Gambia in 2002.

In a statement Mr Rawi, a businessman from south-west London, said: "I am delighted to be back home in England, with my family."

He added: "My nightmare is finally at an end."

I also feel great sorrow for the other nine British residents who remain prisoners in Guantanamo Bay

Bisher al-Rawi

On Thursday, Foreign Secretary Margaret Beckett said it had been agreed with the US authorities that he would be returned to the UK, but officials have not disclosed precisely when the detainee was freed.

"As happy as I am to be home though, leaving my best friend Jamil al-Banna behind in Guantanamo Bay makes my freedom bittersweet," Mr Rawi said in a statement released through the law firm Reprieve.

"Jamil was arrested with me in the Gambia on exactly the same unfounded allegations, yet he is still a prisoner.

"I also feel great sorrow for the other nine British residents who remain prisoners in Guantanamo Bay.

'Misinformation'

"The extreme isolation they are going through is one of the most profoundly difficult things to endure. I know that all too well."

Mr Rawi also paid tribute to all those who campaigned for his release.

His lawyer, Zachary Katznelson, gave further details on why Mr Rawi was originally arrested.

He said a "suspicious device" was found in his client's luggage but added that it turned out to be a battery charger.

Mr Katznelson added: "So it was misinformation that started this chain of events, though unfortunately that led to him first being taken by the CIA to Afghanistan to an underground prison of 24 hour darkness with rats everywhere, to then being taken to Guantanamo - and it took years to right this wrong."

He accused the American authorities of treating Mr Rawi with "brutality".

Mr Katznelson went on: "Right to the end they treated him with brutality, on the way to the plane in Guantanamo - they knew he was leaving - they insisted still on shackling him, blindfolding him, putting on earmuffs so he couldn't hear a thing and keeping him in the back of a very hot , very confined van on the way to the plane."

However the lawyer praised the way the British authorities treated his client after the handover.

False dawns

His constituency MP, Lib Dem Edward Davey, described the news as "fantastic".

He said: "There were many, many months of despair punctured by a few false dawns.

"Yet the sense that a huge injustice was being done kept the family and the team of campaigners together."

Mr Davey said the government must ask British officials in the US to negotiate for the return of other UK residents in the US detention camp.

Meanwhile, Sarah Teather, Mr Banna's MP, said Britain had a moral duty to get her constituent home.

Secret police

British officials have long refused to represent resident foreigners held at Guantanamo, but took up Mr Rawi's case after it was disclosed he had previously co-operated with MI5.

Mr Rawi, an Iraqi citizen with UK residency, was reportedly sent to England in 1985 after his father was arrested by Saddam Hussein's secret police.

Mr Banna is a Jordanian refugee who had been living in north-west London.

Both men were alleged to have been associated with al-Qaeda through their connection with the London-based radical Muslim cleric Abu Qatada.

Mr Rawi and Mr Banna have denied any involvement with Islamic terrorism.