Updated

Pakistan will be giving the Taliban militia who rule Afghanistan an ultimatum: Hand over Usama bin Laden or else.

A group of top Pakistani delegates will travel to the Taliban's headquarters in the southwest Afghan city of Kandahar Monday, a senior Pakistani official said on condition of anonymity. It will deliver a simple message: either give up bin Laden, the leading suspect in the terrorist attacks on New York and Washington, or risk massive retaliation by an international coalition.

The source did not say whether the Taliban would be given a deadline to comply.

Bin Laden has denied any connection to the attacks, though he has praised them. On Sunday, he reiterated his denial in a statement read by Qatar's al-Jazeera satellite television channel.

"I stress that I have not carried out this act, which appears to have been carried out by individuals with their own motivation," read the al-Jazeera announcer from the statement.

Fox News has learned that U.S  officials were alerted by the Israeli foreign intelligence service, the Mossad, in August that a major attack was being planned by groups associated with, or even directly run by, bin Laden.

According to three sources, two senior Israeli operatives came to the U.S. and warned both the FBI and the CIA that as many as 200 terrorists were in the country and preparing a "large-scale operation." The information was apparently not specific and did not include a target, but the time frame was called "imminent."

Bin Laden, the exiled Saudi millionaire already indicted in the United States on charges of masterminding the bombings of two U.S. embassies in Africa in 1998, has been living in Afghanistan since 1996. The Taliban have steadfastly refused to hand him over despite two rounds of U.N. sanctions that have cut off funds to the national airline and isolated Taliban leaders.

The Taliban say bin Laden is a guest. The Taliban's reclusive leader, Mullah Mohammed Omar, has said in the past that delivering bin Laden to non-Muslims would be akin to betraying a tenet of Islam.

On Sunday, the Taliban called an "urgent" meeting of clerics from throughout Afghanistan. At that meeting the clerics voiced their support for the regime, condemned the United States and demanded proof of bin Laden's involvement in the airborne attacks on the World Trade Center's twin towers and the Pentagon.

The devoutly religious Taliban, or "students" in Arabic, arose from the religious schools of southwestern Afghanistan and quickly took over much of the war-scarred country in 1998. Despite their extremist interpretations of Islamic law, or sharia, the Taliban's reputation for brutal honesty won them grudging support from a population weary of 20 years of chaotic rule by rapacious warlords.

Consisting mainly of semiliterate villagers from the Afghan provinces, the Taliban have received little international support. Only three countries — Pakistan, the United Arab Emirates and Saudi Arabia, which follows a similarly harsh brand of sharia — have recognized them as the legitimate government of Afghanistan.

Iranian troops rushed Sunday to seal the 560-mile frontier with Afghanistan. The Shiite Islamic government in Teheran is a bitter enemy of the Sunni Muslim Taliban, accusing them of perverting Islamic law, and is aiding the Northern Alliance, which controls a sliver of Afghanistan near the border of the former Soviet republic of Tajikistan.

"Islamic countries who see the Taliban as an embarrassment will not really care if the United States strikes against them," an anonymous Iranian analyst told Reuters. "Their understanding of religion is so backward and crude, they cannot rally other Muslim countries to support them."

Iranian reformers, including President Mohammed Khatami, condemned Tuesday's attacks upon the United States, while hardline conservatives praised them, reflecting Iran's deep political divisions. Reuters reported Sunday that the mayor of Teheran, along with the head of the city council, had sent a letter of condolence to New York City Mayor Rudolph Giuliani.

"The news about the recent terrorist acts which took many innocent lives in New York caused deep grief and sorrow," said the letter by Mayor Morteza Alviri and city council head Mohammed Atrianfar. "Undoubtedly, this act is not just against New Yorkers, but all humanity."

Meanwhile, intelligence officials from India, Pakistan's historical foe, said they had provided the United States with extensive information about Islamic militant groups operating along the Afghan-Pakistani border.

Tajikistan, however, ruled out letting Western nations use its territory to launch attacks on Afghanistan, echoing comments made by Russian officials last week.

In Pakistan, President Musharraf, a military leader who seized power from an Islamist civilian government friendly to the Taliban, met with politicians, newspaper editors and Islamic clerics, seeking support for his promise to give "full support" to the United States.

Reuters reported Sunday that Musharraf said that if an international coalition forms against the Taliban, "Pakistan is compelled to be there." He told the leaders to prepare for the United States and other Western powers using Pakistani ports and airspace, and even for Western troops to be based in Pakistan if necessary.

But in a telephone conversation with President Bush Saturday night, President Musharraf reportedly stressed to Bush that the inclusion of India or Israel in a coalition would make it difficult for Pakistan to play a role.

Pakistani sources said that Musharraf was not bargaining for Pakistan's cooperation. "He made clear that this is not the time to ask the United States for a quid pro quo, for bargaining," a newspaper editor at Sunday's meeting told Reuters. "This is a time for principles."

Appearing on CNN Sunday afternoon, the Pakistani Ambassador to the U.S., Maheela Lodhi, did not comment on that allegation. She did stress, however, that a coalition against the Taliban must have a strong "Islamic component," and that the Pakistani demand to hand over bin Laden was a "diplomatic option" that must be exercised before the use of force.

Lodhi added that the delegation might not make it to Kandahar Monday, as any flight into or out of Afghanistan must be approved by the United Nations, which has placed travel sanctions on the Taliban.

Some of Pakistan's religious leaders have already been approached by the Pakistani military to use their influence with the Taliban to get them to hand over bin Laden. They have refused.

"We told the government that we're very sorry but we can't do that and we don't have that kind of influence over the Taliban," said Amir-ul Azeem, a spokesman for Pakistan's best-organized religious party, the Jamaat-e-Islami, or Party of Islam.

Pakistan's declaration of "full support" drew widespread protest Sunday from hard-line Islamists. Demonstrators burned U.S. flags, shouted their support of bin Laden, and warned the government they would take up arms for Afghanistan's ruling Taliban militia.

"If Afghanistan is attacked, we will take part in the fight against America," shouted militant Muslim leader Abdul Ahad to an estimated 1,000 demonstrators in northwest Pakistan near the Afghan border. Protesters also shouted anti-American slogans in the federal capital, Islamabad.

Most of Pakistan's 140 million people are devout but relatively moderate Muslims, but there are several strong militant Islamic groups operating in the country and tens of thousands of religious schools that turn out young boys dedicated to jihad — holy war. Most of these militant groups are well armed and could pose a threat to the rule of President Musharraf.

Fox News' Carl Cameron, Marla Lehner, Paul Wagenseil and the Associated Press contributed to this report