The Pentagon remained skeptical of Taliban claims Saturday that Usama bin Laden has fled Afghanistan while the White House exerted pressure on the Northern Alliance to cooperate with plans for a power-sharing government.

"Usama has left Afghanistan with his children and his wives, and we have no idea where he has gone," Taliban envoy Abdul Salam Zaeef said at a border crossing between Afghanistan and Pakistan.

Zaeef later said he meant only that bin Laden was outside areas under Taliban control.

Pentagon spokesman Glenn Flood said the U.S. military had no evidence bin Laden wasn't still in Afghanistan. He said the Taliban could be trying to misdirect the hunt for bin Laden to protect him.

"Our search continues," Flood said.

The Taliban have issued conflicting reports about bin Laden's whereabouts since even before the U.S.-led airstrikes on Afghanistan began.

Even as the hunt for bin Laden continues, plans for a future coalition government seem in question. The Northern Alliance has taken control of two-thirds of the country in a week — speed that has overtaken U.N. and U.S. plans for a power-sharing government to replace the Taliban.

"It's all happened quicker than we thought," Britain's U.N. ambassador, Sir Jeremy Greenstock, said in an interview with BBC radio on Saturday. "We didn't realize the Taliban were such a house of cards."

U.N. envoy to Afghanistan Lakhdar Brahimi has outlined plans for a transitional government backed by a multinational security force, and is attempting to organize a meeting between Afghanistan's many tribal groups. Where the meeting would be held is in question.

The U.S. originally had secured a promise from the alliance not to take Kabul, and the U.N. had plans for a meeting on "neutral" territory. After the alliance took Kabul, however, it invited all Afghan factions except for the Taliban to come to the city and discuss the next government. Now, the U.S. wants to pressure the alliance into holding the meeting somewhere else, despite the outstanding invitations.

A White House official speaking on condition of anonymity said Saturday that the administration does not want to force a government on Afghans, but that the new government must reflect the country's ethnic diversity.

Currently, leaders of the various factions in the Northern Alliance are taking control of the areas of the country taken from the Taliban. Further complicating plans for a coalition government is the return of former president Burhanuddin Rabbani, whose faction dominates the alliance toppled by the Taliban in 1996.

"It's an extraordinarily difficult situation in which the U.S. and its allies are not in a position to exert control, or even significant influence, over their local allies on the ground whose military victory they smoothed the path for," said former Canadian ambassador David Malone, president of the International Peace Academy, a New York think tank.

It isn't clear what would follow a Northern Alliance refusal to cooperate with U.S. and U.N. suggestions.

"You can't just move in behind a load of warlords and start taking over a capital city belonging to another country," Greenstock said.

The Ground War

The Pentagon estimated that the Taliban have lost control of two-thirds of the country. Rear Adm. John Stufflebeem, the deputy director of operations for the Joint Chiefs of Staff, said the areas around Kandahar in the south and Kunduz in the north remained in flux.

Kandahar itself was possibly up for grabs, as a disputed report suggested that the Taliban's supreme leader was ready to flee for the hills, leaving the Taliban headquarters to allied Pashtun commanders.

One traveler from Kandahar who reached the border with Pakistan, Abdul Bari Hairan, said the Taliban were still in control of the center of the city but more of them had been moved to defensive positions south of town.

He said there appeared to be no functioning civil administration in the city, which has been repeatedly pounded by U.S. bombing, and that the population was divided over its loyalties.

If Omar and the Taliban were to leave Kandahar, it would allow the Taliban to give up control of the city to Pashtuns who have a good working relationship with the group, rather than risk the city being overrun by hostile forces.

But on the other hand, it would leave the group without any major cities under their control and reduce the movement to little more than a guerrilla force in the hills of southern Afghanistan.

Elsewhere in the south, the anti-Taliban forces appeared to be gaining ground.

The Taliban retreated from southwest Farah province and moved to neighboring Helmund, the AIP reported Saturday.

Hamid Karzai, a Pashtun leader who has been trying to organize an anti-Taliban uprising, said that he was now in control of Tarin Kot, the capital of Uruzgan province, which borders Kandahar province to the north.

On Friday, Defense Secretary Donald H. Rumsfeld said that "hundreds" of U.S. special forces have been fighting the Taliban and Al Qaeda on the ground in Afghanistan, and that some of the American soldiers were on horseback.

"They're killing Taliban that won't surrender and Al Qaeda that are trying to move from one place to another," he said, without elaborating.

There have been no U.S. deaths, he said, while flying to Great Lakes, Ill., where he was to address the graduating class at the Naval Training Center.

Troops from U.S.-allied countries also are on the ground, Rumsfeld said, but he would not identify those countries.

The Air War

Meanwhile, the U.S.-led airstrikes continue, unabated by the beginning of the Muslim holy month of Ramadan.

In the north of Afghanistan, a U.S. B-52 bomber and attack jets kept up constant bombardment of Taliban positions in the hills outside the city of Kunduz. Taliban troops are surrounded in the city, their last stronghold in the north.

Refugees coming out of Kunduz said U.S. strikes hit the main Taliban headquarters within the city Friday, setting it on fire and killing many Taliban.

U.S. bombs were hitting hard at Taliban defenses, taking out a number of artillery pieces and troops, refugees said.

The defenders include an estimated 2,000 to 3,000 foreigners loyal to bin Laden. They are much less likely than Afghan Taliban to simply negotiate a surrender or slip away, as the bulk of Taliban forces did in the northern city of Mazar-e-Sharif and in Kabul.

The U.S. Central Command said an errant U.S. bomb damaged a mosque in the town of Khost, in eastern Afghanistan near the Pakistan border, on Friday, the first day of Ramadan. It said it did know of any casualties.

On Saturday, France's defense minister said that up to 10 French Mirage 2000 warplanes will attack strongholds of bin Laden's Al Qaeda terror network in missions beginning in the next two weeks.

Rumsfeld confirmed reports that higher-level Taliban leaders have been captured by opposition Afghan forces and American officials are planning to interrogate them.

A notebook, including detailed plans of various terrorist attacks in Turkish language, was found in a camp in Jalalabad deserted by Al Qaeda, private CNN-Turk television said Saturday. The seizure would be the first sign that terrorists from Turkey or those who speak fluent Turkish were trained in the ranks of Al Qaeda along with Arabs and several other foreign nationals.

The Associated Press contributed to this report.