KABUL, Afghanistan – Osama bin Laden and fugitive Taliban chief Mullah Mohammed Omar are not believed to be in Afghanistan, American ambassador Zalmay Khalilzad said yesterday, a day after a purported commander of the rebel group said the pair are alive and well.

Despite the failure to catch Mr. bin Laden since the September 11 attacks, Mr. Khalilzad said “a lot of progress” has been made in fighting his Al Qaeda terror network.

“Mullah Omar is not in Afghanistan. I do not believe that Osama is in Afghanistan,” the outgoing U.S. ambassador said at a news conference in Kabul. He did not say where the two were believed to be hiding. American officials have repeatedly said the fugitive Al Qaeda leader is thought to be some place in the rugged mountains between Afghanistan and Pakistan.

“It is not an easy job to find one person, maybe with some [people] helping him … in a vast region,” he said. “It requires timely intelligence.”

It was not clear how much control Mr. bin Laden still has over Al Qaeda, Mr. Khalilzad said. “Significant numbers of the leaders of Al Qaeda have been captured. Their network has been disrupted … the financial network has also been disrupted,” he said.

Mr. Khalilzad added that the capture of Mr. bin Laden was symbolically very important, and “sooner or later I believe firmly that he will be caught.”

The president of Pakistan, General Pervez Musharraf, said during a visit to Australia this week that his government doesn’t “have a clear idea” where Mr. bin Laden is hiding. He claimed yesterday that his security forces have “broken the back” of Al Qaeda in Pakistan.

Mr. Khalilzad said catching Mr. bin Laden and Mullah Omar required the cooperation of several governments, which, he added, should not allow terrorists to use their territory for “propaganda purposes against Afghanistan.”

The comments appeared to be a veiled criticism of Pakistan. On Wednesday, Pakistan’s Geo TV broadcast an interview with a man it identified as Taliban military commander Mullah Akhtar Usmani, a former Afghan aviation minister, who said Mr. bin Laden was “absolutely fine.” He would not specify where Mr. bin Laden was hiding.

Pakistani officials declined to comment yesterday on Mr. Khalilzad’s remarks.

Geo said the interview was recorded last week. A senior journalist at the independent station said it was conducted near the Afghan town of Spin Boldak, near the Pakistani border.

A spokesman for the Afghan Defense Ministry, General Zaher Azimi, said yesterday that the interview was “not serious” and wouldn’t help the rebels. He questioned why the man claiming to be Mullah Usmani was afraid to show his face, though he stopped short of questioning his identity.

“He was just saying the same thing as usual,” General Azimi said. “This doesn’t make any difference in terms of improving their military or political situation.”