WASHINGTON, July 13 President Obama has ordered US security officials to look into allegations that the Bush administration resisted efforts to investigate a CIA-backed Afghan warlord over the killings of hundreds of pro-Taliban prisoners in 2001.

The prisoners were in the custody of troops led by Gen Abdul Rashid Dostum, a prominent Afghan warlord who has served as chief of staff of Afghanistan's post-Taliban army.

The victims included hundreds of Pakistani citizens whose killings contributed to the emergence of Maulana Fazlullah as a militant leader in Swat.

“The indication that this had not been properly investigated just recently was brought to my attention,” President Obama told CNN's Anderson Cooper in an exclusive interview during the president's visit to Ghana.

“So what I've asked my national security team to do is to collect the facts for me that are known, and we'll probably make a decision in terms of how to approach it once we have all of the facts gathered up,” Mr Obama said.

When asked by CNN about whether his administration would support an investigation, President Obama replied “I think that, you know, there are responsibilities that all nations have, even in war. And if it appears that our conduct in some way supported violations of laws of war, than I think that, you know, we have to know about that.”

After the Taliban government was ousted from power in Afghanistan in 2001, Fazlullah's father-in-law, Sufi Mohammad, organised thousands of militants to go to northern Afghanistan to help the Taliban. Most of them were killed by Dostum's men.

When Sufi Mohammad returned to Pakistan, he was arrested and Fazlullah replaced him as a militant leader, vowing to avenge those killed in northern Afghanistan.

Between 300 and 400 of these volunteers, known as Ansar, were trapped in the Sultan Reza School in Mazar-i-Sharif and were killed by Dostum's forces. Hundreds more foreign fighters, including Osama bin Laden's representative to the north of Afghanistan, were later slain in the desperate Taliban uprising in Qala-i-Jangi fortress-prison which was put down by Dostam's troops in November 2001.

Witnesses told The New York Times and Newsweek in 2002 that over a three-day period, hundreds of Taliban prisoners were also stuffed into closed metal shipping containers and given no food or water; many suffocated while being trucked to the prison. Other prisoners were killed when guards shot into the containers.

Most of them were from Pakistan. The bodies were said to have been buried in a mass grave in Dasht-i-Leili, a stretch of desert just outside Shibarghan.

A recently declassified 2002 State Department intelligence report states that one source concluded that about 1,500 Taliban prisoners died, including hundreds of Pakistanis.

The inquiry stems from the deaths of at least 1,000 Taliban prisoners who had surrendered to the US-backed Northern Alliance in late 2001.