The announcement comes a day after the United Nations said it had investigated the site of a mass grave at Dasht-e Leili near the northern town of Sheberghan but had suspended the probe as Afghanistan could not protect witnesses against reprisals.
Sayed Fazl Akbar, spokesman for President Hamid Karzai, said the Afghan government had yet to receive an official request from the United States for an investigation, but was ready to launch one itself or allow the international community to do so.
"Afghanistan is ready to investigate it," said Akbar. "We will do what we can and if we cannot do it then we will ask the international community to do it. In reality, since the world takes this issue seriously, Afghanistan wants to pursue it, too."
He said the reported deaths happened during a power vacuum in Afghanistan before Karzai was installed as leader of the post-Taliban government in Kabul in late December.
"These types of incidents have taken place in several parts of Afghanistan at the time of the Taliban collapse. All have happened before the establishment of the interim government," Akbar emphasized.
The Boston-based organization Physicians for Human Rights first revealed the existence of the mass graves early in May.
It said it believed the graves contained bodies of hundreds of Taliban and other prisoners captured by Washington's Afghan allies towards the end of the U.S. campaign to drive the Taliban out of power, launched after the September 11 attacks on the United States.
The prisoners were in the hands of forces loyal to warlord General Abdul Rashid Dostum, part of the Northern Alliance.
Newsweek magazine reported over the weekend that more than 1,000 of the prisoners allegedly died while in transport in containers after they surrendered.
In response, the United States said on Monday it was pressing the Afghan government to investigate the allegations.
The United Nations said the deaths appeared to be the result of suffocation in Dasht-e Leili, where thousands of other Taliban prisoners had been buried after being killed by the forces of Northern Alliance commander General Abdul Malik in 1997.
"The investigation confirmed the existence of a large grave area of recent origin and that three bodies were exhumed for autopsy," said Manoel de Almeida e Silva, the U.N. spokesman for Afghanistan. "Absence of blunt force trauma, sharp force injury or firearm injury led the team to conclude that the cause of death was consistent with death due to suffocation."
The U.N. spokesman added that the international body believes that any further forensic work done at the site where the bodies were found should begin only "after an effective witness protection scheme has been put in place."
He adds that "there is no forensic expertise at this point in the country and if any investigation were to be undertaken, it would need to have - most likely - international expertise."
Serious human rights abuses have been committed by various rival factions including the Taliban during the past 23 years of occupation and civil war in Afghanistan.
Dostum, under Western pressure and helped by the International Committee of the Red Cross, has eased the misery of captives at Sheberghan jail.
On a recent visit, a Reuters team saw Afghan and Pakistani inmates crammed 20 to a cell, many sleeping on bare stone floors and more than a dozen suffering from tuberculosis.
But there was none of the severe malnutrition that shocked a visiting European Union ambassador, Klaus-Peter Klaiber of Germany, in May into comparing conditions with the infamous Nazi death camp of Auschwitz.
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