The US military has drawn up plans to continue holding Afghan prisoners it deems a threat in a "unilateral" prison complex on Bagram airbase even after it hands control of the main detention facility to the Afghan government next year.

An empty room is prepared for a prison at a newly built US run Parwan Detention Facility in Bagram north of Kabul, Afghanistan on Friday, Aug 27, 2010. (AP Photo/Musadeq Sadeq) US military authorities are expecting to retain control part of the existing Bagram prison to hold "security threats," as well as prisoners who were arrested outside the country and flown into Afghanistan on rendition flights, according to the admiral in charge of overseeing US detention operations in the country.

Vice-Admiral Robert Harward, the head of Joint Task Force 435, which runs US detentions in Afghanistan, was quoted on Wednesday by the Wall Street Journal admitting that the handover of Bagram was not expected to include all the prisoners currently being held there.

"I anticipate having a subset of unilateral US detention operations, including Pakistanis we can't repatriate and enduring security threats," the admiral said.

The prisoners would be held in one of Bagram's blocks which would remain under the control of the US military. The proposal has been slammed by legal campaigners, who say that it would effectively see dozens of prisoners held beyond the rule of law with no clear means of challenging their detention.

"This proposal for a US 'prison within a prison' at Bagram reveals that the operative principle at the heart of Obama's overseas detention policy is to maintain a clear continuity with the worst practises of the Bush-era," said Clara Gutteridge, deputy director of the secret prisons and renditions team at the legal charity Reprieve.

The plan is also likely to be met with opposition in Afghanistan, where there is a widespread resentment at the US military detention of Afghan citizens. In June's government-run peace jirga, delegates demanded that prisoners being held by the US military were either charged with a crime or released.

The handover plan is part of an initiative to bolster the government of Hamid Karzai, the Afghan president, amid criticism that not enough has been done by Afghan authorities to answer concerns that many of the US military's prisoners are being wrongly held.

Detention overhaul

The past year has seen a substantial overhaul of US detention operations in Afghanistan, with improved mechanisms for prisoners to challenge their captivity, and full trials in Afghan courts. More than 200 detainees have been released from prisons this year, and it was widely assumed that many more would follow after the handover.

But with many of the prisoners held on the basis of a classified evidence, which the US refuses to submit to Afghan courts, concerns have been raised that for some, no regular legal proceedings will take place.

Harward has said that under proposals for a continuation of American detentions, these prisoners are to either be handed to Afghan authorities, unilaterally released by the Americans, or, if they are deemed a "continuing security threat," kept in the American-controlled wing of the prison. US officials say they expect to maintain control of up to 100 prisoners after the handover.

Harward said earlier this year that any continued US control of prisoners in Afghanistan would only occur if the government of Afghanistan "desired" it, and suggested that only foreign prisoners, who could not be handed over to the Afghans, would remain under US control.

The prospect of continued long-term American detention in Afghanistan has raised the possibility of a new round of renditions into the country involving prisoners taken by the US military on secret operations against Al Qaeda-linked groups in places like Yemen and Somalia.

Gutteridge told Al Jazeera that Obama has never ruled out using rendition to move prisoners between countries, adding that there there was confusion over the details of his administration's detention policy, which the president pledged to make public soon after taking office.

"Despite commitments to transparency over a year ago, Obama's detention policy still remains almost entirely secret," she said. "Obama must publish the results of his detention review that he promised last summer, and come clean on his increasingly worrying detention policy."