|Former detainees in Afghanistan have alleged mistreatment at the hands of the US military in a secret prison. [EPA]
Former US military prisoners in Afghanistan have said that they were abused in a secret prison on Bagram airbase as recently as this year, raising fears that detainee mistreatment has continued despite an overhaul of US detention operations in the country.
The abuse - which includes exposure to extreme temperatures, lack of adequate food and bedding, lack of natural light and interference with religious duties - is alleged to have occurred at a secret "screening" facility on the military base north of Kabul.
The existence of the site, known amongst Afghans as the "Tor Jail", has never been admitted by US authorities, although it does acknowledge it runs a number of field sites in which prisoners are held immediately after being captured.
Prisoners are kept at the field sites before either being handed to Afghan authorities, released, or transferred to the main US detention facility at Parwan, on the edge of Bagram airbase.
The US task force responsible for running detentions in the Afghanistan insists that treatment in all its facilities meets international standards.
But a report released this week by the US-based Open Society Foundation, details the testimony of 18 detainees held at the Tor Prison who say they were mistreated there.
The testimony includes repeated claims that their cells were kept uncomfortably cold so they were unable to sleep, that they were given inedible food, and that bright lights were kept on in windowless cells 24 hours a day.
Such treatment would not only fall short of international standards for the treatment of prisoners, but also would run counter to US military's own guidelines on the issue, which says prisoners should not be exposed to "excessive or inadequate heat, light, or ventilation".
The differences between the secretive Tor Prison and the main Bagram site have raised questions about whether the smaller site is being run by a different military agency to other detention sites in the country, which come under the mandate of Joint Task Force 435 (JTF 435).
Jonathan Horowitz, the author of the report, told Al Jazeera that there appeared to be a link between the Tor Prison and US special forces activity in Afghanistan.
"JTF 435 does not run the facility," he said. "The facility does seem to have tight links with forces operating under Joint Special Operations Command (JSOC). Whether they are the only ones in charge, I don't know."
"It's worth noting that at the Detention Facility in Parwan [the main Bagram prison], there are also interrogators and isolations cells,' he said.
"One of the big differences between the two sites is transparency. I assume that those in Tor Jail think they benefit from its secretive nature and don't want to give that up."
The allegations have come to light as the US military oversees a much-publicised effort to improve its record on detainee treatment in Afghanistan. Improved prison facilities have been built, and the International Committee of the Red Cross (ICRC) has been given better access to those held in US detention.
Eighteen prisoners who passed through the site were interviewed for the report. Half of them said that they had been taken to the prison in 2009 and 2010, after Barack Obama, the US president, had already ordered an overhaul of detention operations in Afghanistan.
The US military has denied that it runs secret prisons in Afghanistan, and said it does not mistreat the prisoners it holds there, insisting that conditions are compliant with both the Geneva Coventions and the military's own guidelines.
Lieutenant Colonel Elizabeth Robbins, a Pentagon spokesperson, said the US department of defence (DoD) "takes all credible allegations of detainee mistreatment very seriously".
"Furthermore, DoD conducts thorough and regular assessments of all of its detention facilities and operations to maintain oversight, accountability and to ensure humane treatment of detainees," she said in an email to Al Jazeera.
The US military does run temporary detention and screening facilities in Afghanistan, "which are classified to preserve operational security," she said. "However, both the ICRC and the respective host nations have knowledge of these facilities ... [and] these facilities are consistent with international and US law."