Afghan and US officials are working on a compromise deal to allow US special forces to stay in a strategically key province near the capital in return for full Afghan control of a controversial jail, a top Kabul official said.

Afghan President Hamid Karzai's previous decision to expel special forces from Wardak province has angered US defense officials who worry their exit could allow insurgents to strengthen their presence in the area and use it as a base to attack Kabul, only 25 kilometers away.

US special forces tasked with fighting the Taliban were scheduled to leave the province a week ago, but US and Afghan officials have told Reuters they are still operating there.

"There might be a compromise on Wardak when the Afghan side is given full control of Bagram prison, which would help Karzai who views the issue as a matter of sovereignty," a senior government official told Reuters at the weekend, speaking on condition of anonymity.

The US partly handed over the high-security prison and around 3,000 suspected Taliban fighters to Afghan control last year, but has not transferred hundreds of Taliban fighters to Afghan custody over concerns they will be released.

During a phone call on Saturday Karzai and US Defense Secretary Chuck Hagel "agreed to use the next week to conduct intensive work with a view to concluding an agreement," the Pentagon said.

The transfer of control of the detention center at Bagram air base is a persistent source of tension, with Karzai's office warning in a statement on Wednesday that "any more delays could harm bilateral relations."

US commanders want to ensure that dangerous prisoners will not return to the battlefield, but Karzai has raised alarms by warning that any "innocent" prisoners being held at the facility will be released.

Karzai ordered US special forces to leave Wardak province after residents complained that they, and Afghans working with them, were torturing and killing civilians, an allegation strongly denied by the US.

Other issues are heating up Afghan-US relations.

A US soldier charged with killing 16 civilians, most of them women and children, near his Army post in Afghanistan is set to undergo a medical review on Sunday to determine his state of mind at the time of the killings and ability to stand trial.

Afghanistan's leading religious body, the National Ulema Council, Saturday warned the presence of US troops in the country would soon be treated as an "occupation" unless the US hands over detainees.

Reuters - AFP