The US has not acknowledged detaining Khaled al-Maqtari

Khaled al-Maqtari told Amnesty International he was held in isolation for more than 28 months without charge or access to any legal representation.

He said he first became a US "ghost detainee" at Abu Ghraib prison in Iraq after being arrested there in 2004.

The US has not acknowledged detaining Mr Maqtari.

CIA spokesman George Little told the BBC: "Apart from transfers to Guantanamo, the CIA does not, as a rule, comment publicly on allegations of who may - or who may not - have been in its custody.

"The agency has run its terrorist detention and interrogation programme in accord with US law."

US President George W Bush did acknowledge the existence of black sites in 2006.

He said the prisons were a vital tool in the US "war on terror" and insisted that the CIA had treated detainees humanely and had not used torture.

In July 2007, Mr Bush issued an executive order which banned "cruel, inhuman or degrading treatment" of terrorist suspects by the CIA, but not its operation of secret facilities. The agency has since declined to say whether it still uses them.

'Ghost detainee'

In his first interview since being released by the Yemeni authorities in May last year, Mr Maqtari described the torture and ill-treatment he said he had suffered at the hands of the US military and CIA while in secret custody.

He describes being subjected to international crimes such as enforced disappearance and torture, yet these allegations have never been investigated

Anne FitzGerald

Amnesty International

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He said he was initially arrested in Iraq in January 2004, when the US military raided a suspected arms market in Falluja.

He is believed to have then been handed to US Military Intelligence on suspicion of being a foreign insurgent.

He said he was then transferred to Abu Ghraib, where he alleged he was subjected to a regime of beatings, sleep deprivation, suspension upside-down in painful positions, intimidation by dogs and induced hypothermia.

After nine days of interrogation at Abu Ghraib, Mr Maqtari said he was flown to a secret CIA detention facility in Afghanistan and held there for three months.

Amnesty says it has obtained flight records which show that a plane operated by an alleged CIA front company flew from Baghdad to Kabul nine days after his arrest.

Mr Maqtari sketched how he was allegedly tortured in Abu Ghraib

Mr Maqtari said that while in Afghanistan he was subjected to further torture and ill-treatment, including prolonged solitary confinement, the use of stress positions, sleep deprivation, exposure to extremes of hot and cold, sensory deprivation and disruption with bright lighting and loud music or sound effects.

"It was not really music but noise to scare you, like from one of those scary movies," he told Amnesty.

"I was scared, there were no dogs but there was noise there. Whenever you try to sleep, they bang on the door loudly and violently."

During the lapses in the music and sound effects, he was able to speak to other detainees and deduced that there were about 20 others being held in the cell around him, including Majid Khan, one of the "high value" detainees transferred to Guantanamo Bay in September 2006, according to Amnesty.

'Absence of accountability'

Mr Maqtari said that in late April 2004 he and a number of other detainees were transferred to another CIA black site, possibly in eastern Europe and held there in isolation for a further 28 months.

A report found EU states knew of secret CIA flights over their territory

The Council of Europe has found evidence that the CIA ran secret jails in Poland and Romania between 2003 and 2005 to interrogate suspects.

Throughout his detention, Mr Maqtari did not have access to lawyers, relatives, the International Committee of the Red Cross (ICRC) or any person other than his interrogators and the other US personnel involved, Amnesty said.

Mr Maqtari was eventually handed over by the CIA in the summer of 2006 to the Yemeni authorities, who continued to hold him without charges until May 2007, the rights group said.

"Khaled al-Maqtari's account sheds more light on the US's unlawful conduct in the 'war on terror'," said Anne FitzGerald, a senior adviser at Amnesty.

"He describes being subjected to international crimes such as enforced disappearance and torture, yet these allegations have never been investigated," she added.

"The secrecy surrounding the programme goes hand-in-hand with a complete absence of accountability," the Amnesty International adviser said.

The US state department said it had no comment to give on Mr Maqtari's case.