The UN has gathered enough evidence to begin a criminal investigation into the allegation that almost 1,000 captured Taliban are buried in mass graves in Afghanistan, it was revealed last night.

A confidential UN memo leaked to the American magazine Newsweek, said disturbing evidence had been uncovered which substantiated the rumors of mass graves in an area called Dasht-i-Laili.

The captives allegedly died after being packed into sealed cargo containers en route from Konduz to the Northern Alliance prison at Sheberghan.

The Newsweek report cites the discovery of bodies with little clothing and no obvious trauma as consistent with the claim that they had died of suffocation in the containers. A witness quoted in the memo put the number at 960.

There appears to be no evidence that the US knew of the deaths, nor that American officials saw or were involved in putting prisoners into unventilated trucks.

The Guardian reported in June that a former chairman of Amnesty International was calling for an independent inquiry into claims that US troops tortured Taliban prisoners and were complicit in the disappearance of thousands of others during the war.

The call by Andrew McEntee, now a human rights lawyer, was based on a British-made documentary which described thousands of Taliban fighters being corralled into the containers after the battle of Konduz in November.

At the time the jail in Sheberghan, in north-western Afghanistan was under American control. The film, Massacre at Mazar, claimed that large numbers of prisoners died on the journey.

The footage showed areas of compacted red sand, apparently caked with blood, traces of bones, including jaws, and pieces of clothing. But only 15 bodies had been found, the program said.

Washington would not be drawn last night on whether it supported a full-scale inquiry.

The militia leader whose forces allegedly carried out the killings is General Abdul Rashid Dostum, reputedly one of Afghanistan's most ruthless warlords. His spokesman told Newsweek that many people had died of suffocation, but he put the total at 100-120. He said some "were seriously injured and had died en route".

He also said that the treatment of the prisoners would have been colored by the uprising of prisoners at Qala Jangi three days earlier.

"If the incident at Qala Jangi hadn't happened, it's possible that the prisoners would have been transferred more peacefully," he said. "There would have been less irregularities."

He added: "They suffocated. Nobody killed anybody."

The details of the transfer of prisoners was left to much lower ranking officials, he said.

During the war US soldiers stayed close to Gen Dostum, but it remains unclear how much US officials knew about the treatment of prisoners.

"Considering the political sensitivity... and related protection concerns, it is strongly recommended that all activities relevant to this case be brought to a halt until a decision is made concerning the final goal of the exercise: criminal trial, truth commission, other etc," the UN report said.

Even if the US knew nothing of the alleged mistreatment, questions will be asked about its responsibilities when training and fighting alongside its allies.

More than 3,000 Taliban were captured at Konduz.

The Newsweek report, which was based on interviews with people who claimed to have seen the transportation, said fighters promised that they would be released but they were packed into the trucks instead.

The first evidence of using abandoned containers for executing captured enemies was noted in a 1997 UN report. About 1,250 Taliban were left in containers in the desert sun after an assault on Mazar-i-Sharif. The dead were later found to have been grilled black. When the Taliban captured Mazar in 1998 they killed several hundred in a similar fashion.

· US officers have yet to discover any senior al-Qaida leaders among the 600 captives held at Guantanamo Bay, a US intelligence source has told the Los Angeles Times.

The unnamed source said the captives are "mostly low and middle-level" fighters not the "big time guys" who could help to fracture al-Qaida.

© Guardian Newspapers Limited 2002

###