"At first, they took all our clothes off and told us to stand up. When they were interrogating me, I was naked."
Bagram houses one of the main US detention centres
Haji Mirza Mohammed was arrested from his home and accused of working with the Taleban in the autumn of 2004.
He was taken to the nearby infantry base of the US-led coalition at Gardez in south-east Afghanistan.
"For four days, I had my hands cuffed behind me," he says. "They stopped giving me food and I wasn't allowed to sleep."
Haji Mirza's testimony forms part of a new set of allegations of abuses at coalition bases in Afghanistan.
Former detainees have told the BBC they were deprived of sleep and food, put in stress positions and beaten.
A former interpreter has said he witnessed interrogators withholding water as a punishment and using sexual taunts to try to break down prisoners.
A US military spokesman in Afghanistan said he could not deny abuses had taken place, but allegations of misconduct were taken seriously.
At the end of April, the post of United Nations special expert on human rights in Afghanistan was discontinued.
The final incumbent, the Nobel Peace Prize-nominated law professor, Cherif Bassiouni, told the BBC he believed he lost his job after criticising US detention facilities in Afghanistan.
American officials said the country's human rights situation had improved.
According to the Afghan Independent Human Rights Commission, conditions at the coalition's two main prisons at Bagram and Kandahar have improved in recent months, but it is still receiving many complaints about the temporary holding facilities at bases like Gardez, where Haji Mirza was taken.
Another former detainee at the Gardez base, Jannat Gul, said he was forced into a kneeling position in the middle of a room, surrounded by four or five American interrogators.
"They said, 'don't sit back on your heels, don't look to the side'. They were beating me, telling me bad things. They ordered me to stay kneeling until the morning. I was three nights without sleep and then the last night, I had to kneel until morning."
Jannat Gul says he was punched and kicked. At one point, he says, he was told to lie down.
"They picked me up by my neck and said, 'we're going to kill you unless you confess what you did'."
As he describes his experiences, a couple of phrases in English are scattered among the Persian - "put your arms up" is one. The other is, "shut the **** up".
"I'm a farmer," says Jannat Gul, showing his calloused hands.
"I'm not a member of al-Qaeda. Ask the Americans why I was held for 16 months. When they released me, they just said, 'we're very sorry'. That's all they said. If there is such a thing as human rights, I want to ask for my rights."
Another Afghan who has made allegations about interrogation practices at the infantry bases is a former interpreter with the US military.
Wahidullah - which is not his real name - speaks with a southern American accent picked up from the soldiers.
Nearly 200 prisoners were recently freed from Bagram
He uses swear words and military slang, like PUC (persons under control, i.e. detainees) and hooch (tent).
He says he saw detainees given different punishments if they refused to speak.
"PUCs would be told to stand for six hours or forced to kneel on a two-by-four piece of wood for three hours with no water."
He alleges that a detainee at the Asadabad base died after not being given enough water in hot weather over a four-day period.
"He was a young boy, he was strong and he spent three days in the detainee facilities. At that time, it was a mud room with no window."
Wahidullah says he came the next morning and saw the detainee lying on the ground, his hands still cuffed and with spit around his mouth.
"I told the guard he had died and he said, 'no he's just acting'. But when he checked the guy, he found he was dead. They told all the people he'd had a heart attack."
When the BBC put these allegations to the spokesman for the US military in Afghanistan, Col Jim Yonts, he said he did not know if "those things exactly happened", but he had no information to suggest they had.
When asked whether sleep, food or water deprivation or the use of stress positions was permitted, he said he could not discuss the details of an interrogation.
"All I can say is we do not condone the mistreatment of detainees and, as you have seen, we've taken appropriate action when allegations have proved true."
On the specific question of withholding water as a punishment, he said: "Whether or not they're provided with food and water, the key point is we treat them humanely, based on humane law."
He also said it had to be remembered who was in detention.
"They're not normal criminals. They're enemy combatants based on their actions against the Afghan people or US service members."