SLAMABAD, Pakistan, Monday, Sept. 17 — Pakistan sent a group of high-ranking military officers to Afghanistan today to demand that the Taliban government hand over the accused terrorist Osama bin Laden and his top associates to the United States or face almost certain American military action, senior Pakistani officials said.

The group is led by Maj. Gen. Faiz Gilani, one of the top officers in Pakistan's military intelligence wing, the Inter-Services Intelligence directorate, or ISI, which is thought to have unique intelligence on Mr. bin Laden's operations in Afghanistan and his whereabouts.

Pakistan's president, Gen. Pervez Musharraf, had agreed to relay the ultimatum after days of intensive discussions between American and Pakistani officials, in Washington and Islamabad, the Pakistani officials said. But the officials also cautioned that the chances of the Taliban bowing to the American demand were slim.

In the first test of its pledge to make nations choose sides in a war against terrorism, the Bush administration has placed relentless pressure on Pakistan to cooperate in capturing or eliminating Mr. bin Laden, who is suspected of masterminding Tuesday's catastrophic attacks on New York and Washington.

In effect, the Pakistani officials said, American officials had told General Musharraf's government that Washington would use every lever "short of war" to punish Pakistan unless it cooperated.

The officials said that at the meeting in Kandahar, where the delegation arrived this morning, the Taliban leaders would be told that they had "only a few days" to hand over Mr. bin Laden or face an eventual American military attack that would almost certainly target the Taliban as well as Mr. bin Laden, and possibly lead to American troops entering Afghanistan.

Alternatively, the Taliban would be told, according to those officials, that if they agreed to hand over Mr. bin Laden and his associates and close down all his training camps, the Taliban would be left to continue in power.

The choice between confronting the Taliban or cooperating with the United States is a wrenching one for General Musharraf, who leads a chronically unstable and nuclear armed nation of 140 million people, dependent on ties to the West but increasingly lured by radical Islam.

In a sign of just how treacherous he judges the situation to be, General Musharraf spent Sunday in a highly unusual series of meetings with influential Pakistanis, including politicians, newspaper editors, Muslim clerics and dozens of people with links to conservative Islamic groups.

Success in Kandahar would head off an American military operation that would almost certainly involve the use of Pakistan's airfields and airspace. Such an event could set off bitter protests by supporters of Mr. bin Laden and the Taliban in Pakistan, who took to the streets on Sunday in modestly sized rallies across the country. It could even shake or wrench loose General Musharraf's hold on power.

But officials said they rated the chances of the Taliban bowing to the ultimatum as "very poor." The Taliban leader, Mullah Mohammed Omar, has already said in a defiant, warlike radio speech on Friday that he believed that handing over Mr. bin Laden would not spare Afghanistan from an American attack.

If the delegation's mission does fail, Pakistan will almost certainly have to prepare for a central role in what President Bush has repeatedly described as war. In Washington, Secretary of State Colin L. Powell said Sunday that an "an interagency" team of top officials would fly to Islamabad this week to work out the details of that support.

Pakistani officials, however, continued to avoid specifying what Pakistan's role would be, apparently to give General Musharraf time to prepare crucial centers of opinion for steps certain to provoke bitter opposition. "This is not a man who is used to having to sell anything, least of all to politicians, editors and mullahs," said one of those who was at the Sunday meetings. "He's a general, used to telling people what to do, not asking them to support him."

An influential Pakistani who attended some of the Sunday briefings said General Musharraf had already assured President Bush in a telephone call on Saturday that Pakistan would allow the use of its airspace and airfields, if needed, as well as full access to Pakistani intelligence on Mr. bin Laden.

Crucially, too, this participant said, Pakistan has agreed to provide "logistical support" to an American military campaign, apparently including the provision of crucial supplies like fuel.

The only hard-and-fast limits that Pakistan had set, the participant in the briefings said, were that it would not allow its own troops to be deployed alongside an American force in Afghanistan, and that any American military presence on the ground in Pakistan would have to be kept "well out of sight," at remote military bases and airfields.

"Other than that," the participant said, "I got the impression that we will not be pussyfooting about this, that we will give the Americans just about everything they want."

But those who took part in the meetings said General Musharraf had given the impression that he had driven a hard bargain. Among other things, the general was said to have demanded an end to economic sanctions imposed by Washington after Pakistan tested nuclear weapons in 1998, and the lifting of an American ban on weapons sales.

Also on the list, participants said, was a pledge that Washington would assist Pakistan's battered economy by encouraging generous treatment by the International Monetary Fund and the World Bank, and a shift in Pakistan's favor in its dispute with India over the Kashmir region.

If it comes to war, General Musharraf will be committing Pakistan to a war against a neighboring Muslim state, something bound to shock parts of this overwhelmingly Muslim nation whose unquenchable poverty has made it a breeding pool for radical Islamists, including those in the senior echelons of the army.

Although Pakistan's army and police are almost certainly powerful enough to suppress street protests, influential Pakistanis say, General Musharraf, who took power in a coup nearly two years ago, cannot be sure that some of his fellow army commanders might not topple him if he fails to carry them with him.

"If he lets the Americans use Pakistan as a launching pad for operations in Afghanistan, Musharraf will face problems, no doubt about it," a veteran politician said. "But his difficulties will be proportional to the benefits he can bring to Pakistan, and to the length of time it takes for the Americans to achieve their objectives in Afghanistan.

"If the operation is swift and short, Musharraf will be okay, but if it is protracted he'll run into all sorts of political problems."

Regardless of the outcome of today's mission, even locating Mr. bin Laden is less than a certainty. A Pakistani journalist, Jamal Ismail, who represents Abu Dhabi Television in Afghanistan, said on Sunday that he had received a clandestine message from the Taliban saying that Mr. bin Laden had gone. "Our guest has left," Mr. Ismail quoted the message as saying, "and we are not aware of his whereabouts."

Officials in Pakistan, however, noted that the Taliban had made such claims before, only to have the Saudi- born militant reappear in the company of Taliban leaders.

In any case, it was not clear where Mr. bin Laden could go, except into some new hideout in the semi-deserts and mountains that make up much of Afghanistan, which in themselves may provide safe haven enough. As Soviet troops discovered during their disastrous decade occupying Afghanistan in the 1980's, the terrain is among the most rugged and inhospitable on earth.

A Russian official told CNN in Moscow on Sunday that Russia's intelligence service knew where Mr. bin Laden was just before last Tuesday's attacks, but not any more. Pakistan's own intelligence service has said that it, too, does not know Mr. bin Laden's current hideout.

As for Mr. bin Laden himself, the Qatar-based satellite television station Al Jazeera broadcast a statement on Sunday that it attributed to the world's most wanted fugitive. "I would like to assure the world that I did not plan the recent attacks, which seem to have been planned by people for personal reasons," read the message, whose authenticity was impossible to verify. "I have been living in the Islamic Emirate of Afghanistan and following its leaders' rules. The current leader does not allow me to exercise such operations."