KABUL: Afghan President Hamid Karzai on Sunday ordered US special forces out of a central province, saying Afghans working with them had committed torture and murder.

Karzai said the special forces would have to withdraw from Wardak within two weeks as armed Afghan groups they had set up were fuelling "insecurity and instability".

It is another blow to US-led forces, coming the same month Karzai issued a decree ordering an end to local security forces calling in NATO air strikes amid new tensions over civilian casualties.

Karzai took the decision about Wardak in a meeting of the national security council, said presidential spokesman Aimal Faizi.

"The US special forces and illegal armed groups created by them are causing insecurity, instability, and harass local people in this province," he told a press conference.

He said armed individuals "named as US special forces" in Wardak "engage in harassing, annoying, torturing and even murdering innocent people," according to a statement from the presidential office.

The statement cited a recent example in which which nine people disappeared in an operation conducted by this "suspicious force".

In another incident, a student was taken away at night from his home, and his tortured body was found with its throat cut two days later under a bridge, the statement said.

The Americans had rejected having carried out any such operation and the involvement of their special forces, the statement said.

A spokesman for the US military in Afghanistan said he had seen reports of the comments and would seek to discuss the matter with senior Afghan officials.

"We take all allegations of misconduct seriously and go to great lengths to determine the facts surrounding them," he said.

"Until we have had a chance to speak with senior (Afghan) officials about this issue we are not in a position to comment further. This is an important issue that we intend to fully discuss with our Afghan counterparts."

Tensions have been escalating between Afghanistan and the United States, which provides most of the troops in the war-torn country, as the bulk of NATO's 100,000 soldiers prepare to leave by the end of 2014.

Karzai said in February that he was "happy" that foreign forces were leaving Afghanistan, adding that "(Afghans) are the owners of their country".

More than 3,200 NATO troops, mostly Americans, have died in support of Karzai's government in the war since the Taliban were ousted by a US invasion in 2001, but relations between the president and the US are often prickly.