By Hilary Andersson
BBC News, Bagram
Inmates from the old prison at Bagram have been moved elsewhere
Afghan prisoners are being abused in a "secret jail" at Bagram airbase, according to nine witnesses whose stories the BBC has documented.
The abuses are all said to have taken place since US President Barack Obama was elected, promising to end torture.
The US military has denied the existence of a secret detention site and promised to look into allegations.
Bagram was the site of a controversial jail holding hundreds of inmates, who have now been moved to another complex.
The old prison was notorious for allegations of prisoner torture and abuse.
But witnesses told the BBC in interviews or written testimony that abuses continue in a hidden facility.
"They call it the Black Hole," said Sher Agha who spent six days in the facility last autumn.
"When they released us they told us we should not tell our stories to outsiders because that will harm us."
I could not sleep, nobody could sleep because there was a machine that was making noise
Sher Agha and others we interviewed complained their cells were very cold.
"When I wanted to sleep and started shivering with cold I started reciting the holy Koran," he said.
But sleep, according to the prisoners interviewed, is deliberately prevented in this detention site.
"I could not sleep, nobody could sleep because there was a machine that was making noise," said Mirwais, who said he was held in the secret jail for 24 days.
"There was a small camera in my cell, and if you were sleeping they'd come in and disturb you," he added.
The prisoners, who were interviewed separately, all told very similar stories. Most of them said they had been beaten by American soldiers at the point of arrest before being taken to the prison.
Mirwais had half a row of teeth missing, which he said was from being struck with the butt of a gun by an American soldier.
No-one said they were visited by the International Committee of the Red Cross during their detention at the site, and they all said that their families did not know where they were.
In the small concrete cells, the prisoners said, a light was on all the time. They said they could not tell if it was night or day and described this as very disturbing.
Mirwais said he was made to dance to music by American soldiers every time he wanted to use the toilet.
The ex-prisoners said they were imprisoned at the secret jail before being taken to the main detention centre at the Bagram airbase, a new complex called The Detention Facility in Parwan.
Bagram's prisoners were moved to the Parwan complex from the old notorious Bagram prison site on the airbase earlier this year.
In 2002, two prisoners were killed in the Bagram prison while in US custody after being suspended from the ceilings of their cells and brutally beaten.
The BBC was allowed into the new Bagram prison for an hour.
This was one of the first opportunities any outsider has had to set eyes on Bagram's interned prisoners since a jail was first established at Bagram soon after 9/11.
In the new jail, prisoners were being moved around in wheelchairs with goggles and headphones on.
ON BBC RADIO 4
Hilary Andersson investigates detention at Bagram on BBC Radio 4 at 2002 on 11 May 2010.
The goggles were blacked out, and the purpose of the headphones was to block out all sound. Each prisoner was handcuffed and had their legs shackled.
Prisoners are kept in 56 cells, which the prisoners refer to as "cages". The front of the cells are made of mesh, the ceiling is clear, and the other three walls are solid.
Guards can see down into the cells above.
The BBC was told by the military to wear protective eye glasses whilst walking past the mesh cells as prisoners sometimes throw excrement or semen at the guards.
Prisoner accounts we logged painted a much better picture of the Parwan Detention Facility.
The US military itself has admitted that about 80% of those at Bagram are probably not hardened terrorists. It is the process of giving every detainee an internal military trial of sorts, called a Detainee Review Board.
The prisoners are represented by soldiers who are not lawyers.
"To this date, no prisoner has ever seen a lawyer in Bagram", said Tina Foster, who represents several of Bagram's prisoners in cases she has filed in on their behalf in the US. Guantanamo Bay's prisoners are able to see their lawyers.
About 100 prisoners have been released through this process, but due to an increased intake, the number of prisoners at Parwan is now 800, up from about 650 in September 2009.
The BBC put the allegations of ongoing abuses as a secret site on the airbase to the US military at Bagram. The military categorically denied the existence of a secret detention site.
"I've never heard of it. This is the only detention facility in Afghanistan" said Vice Admiral Robert Harward who is in charge of the Detention Facility in Parwan.
The US military promised to investigate any allegations of abuse.