The United States said it was putting pressure on the Afghan government to investigate reports that hundreds of Taliban prisoners died after surrendering last November.
"We are looking into the circumstances surrounding the events that are reported. . . . We've stressed and continue to stress to Afghan authorities the importance of investigating allegations of human rights violations and war crimes," said US State Department official Mr Philip Reeker.
The Boston-based organisation Physicians for Human Rights (PHR) said it was the first time the US government had indicated it was prepared to look into the allegations.
PHR has demanded a commission of inquiry under a UN Security Council mandate to investigate an alleged mass grave site at Dasht-e Leili near the northern town of Sheberghan.
The group believes the grave contains the bodies of hundreds of Taliban and other prisoners captured by Washington's Afghan allies towards the end of the US military campaign against the Taliban.
In its August 26th issue, Newsweekquoted an Afghan human rights campaigner as saying more than 1,000 of the prisoners died while in transport in containers after they surrendered to US-backed Northern Alliance.
The prisoners were in the hands of forces loyal to warlord Gen Abdul Rashid Dostum, part of the Northern Alliance.