Human Rights Watch on Wednesday called for a "thorough and impartial investigation" into allegations US special forces were complicit in the torture and killings of Afghan civilians.

The US-based rights group cited a report published Wednesday in Rolling Stone that raised fresh questions about the role of US Army Green Berets in the deaths of 18 men in 2012-2013 in the Nerkh district of Wardak province, outside the capital Kabul.

"The Nerkh incidents should be investigated rigorously, impartially, and transparently," Andrea Prasow, senior counterterrorism counsel at Human Rights Watch, said in a statement.

"While it is clear that crimes occurred, US authorities need to establish what exactly happened and who is responsible."

He added that the United States had a poor record of prosecuting rights abuses allegedly committed by American forces during the 12-year-old war in Afghanistan.

The Rolling Stone article, citing interviews with Afghan villagers, relatives and local officials, alleges that remains of 10 of the victims who had "disappeared" were found buried near the base of the Green Beret unit, known as ODA 324.

The article quoted a local Afghan who was detained by US forces alleging he saw an Afghan interpreter, Zikria Kandahari, execute his neighbor with American troops standing by and doing nothing to stop him.

The interpreter, Kandahari, was arrested in May and has been accused by Afghan authorities of torturing and murdering civilians while working for the Green Berets. But he has alleged he was following American orders.

Based on interviews with villagers, the magazine article suggested US forces may have turned a blind eye to some murders, engaged in torture of some detainees and even some killings.

After the first revelations of possible war crimes emerged, President Hamid Karzai ordered the American special forces to leave the province in February. Under a compromise deal, the Green Beret unit left the Nerkh district in March but US forces remained elsewhere in Wardak.

The US-led NATO mission in Afghanistan, the International Security Assistance Force (ISAF), carried out an investigation but found no evidence of wrongdoing by the special forces team, officials said.

In July, the US Army's Criminal Investigative Command launched a fresh probe into the killings.

Rolling Stone, citing military sources, said the investigation came after the International Committee of the Red Cross provided new evidence in the case.

"We currently have an open and ongoing criminal investigation," Chris Grey, spokesman for the Criminal Investigation Command, told AFP.

Special agents from the command opened their investigation after being informed of allegations on July 17 from the legal adviser at ISAF headquarters in Kabul, he added.

Military authorities had no plans to release information on the case to protect the integrity of the investigation, officials said.