Filed at 7:54 a.m. ET

KABUL (Reuters) - After a diplomatic initiative failed, Pakistan on Friday sent a team of revered Muslim clerics to try to persuade Afghan Taliban leader Mullah Mohammad Omar to hand over Saudi-born fugitive Osama bin Laden and avoid a punishing U.S. assault.

Mullah Omar's position has never appeared more perilous. He is under siege from the rest of the world over his hospitality to bin Laden, the chief suspect in this month's U.S. suicide plane attacks, and under attack from opposition fighters within.

As the clerics flew from Islamabad to the southern city of Kandahar, residents in the Afghan capital scurried for cover when a test of its air defenses was mistaken for an American attack.

Bursts of continuous firing could be heard from the hills around Kabul, where Taliban fighters have dug in air defenses against expected U.S. attacks. A Taliban official confirmed the firing was a test.

``We all thought the war with America had began,'' said one resident, who was having breakfast when the firing began.

``The sudden repeated firing was like a shock and a signal that my turn to die had come.''

Preachers addressing Friday prayers reflected the tension -- endorsing an earlier decision of Afghan clerics to ask bin Laden to leave voluntarily but calling on the population to fight if the United States does attack.

``Jihad is the only way and we will not sit quietly by if America attacks us. All Muslims must defend their brothers and Osama in Afghanistan if that becomes the bottom line,'' said a preacher at one of the city's main mosques.

As the city prepared for the worst, the team of clerics from the Deobandi school of Islam -- from where the Taliban draw their strict interpretation of the Koran -- arrived in Kandahar to warn the Afghan leadership of the danger they face in continuing to shelter bin Laden.

CLERICS TO REINFORCE RECOMMENDATIONS

The United States has vowed to hunt down the Saudi-born fugitive and punish his Taliban protectors.

``I think the ulema (clerics), all respected by the Taliban, are going to reinforce the recommendation of the Afghan clerics who met in Kabul,'' said a source close to the clerics.

A meeting of 1,000 of Afghanistan's leading clerics on September 20 issued an edict urging bin Laden to leave the country of his own free will and in his own time.

``They are going to convey a similar message,'' the Pakistani source said.

All the clerics are Deobandis -- a school of thought that originated in India 150 years ago from a seminary in Deoband village and to which the Taliban strictly adhere.

It was unclear whether they would be able to influence Mullah Omar. A team of high-ranking Pakistani military and diplomatic officials failed this month to convey to his puritanical movement the gravity of their situation.

Pakistan, which gave the Taliban key early backing and helped them seize power, is now the only country with diplomatic relations with the Afghan leadership and the last conduit through which any attempt to avoid conflict can be channeled.

On Thursday, U.S. civil rights leader Jesse Jackson said he was considering a Taliban invitation to mediate -- a scenario seen in the region as unlikely given that Jackson is an ordained Christian minister and Mullah Omar has only met two non-Muslims in his life.

The Taliban said they had not invited Jackson, but welcomed his offer.

REALISTIC INFLUENCE

A more realistic influence was likely to be Mufti Nizamuddin Shamzai, one of the most senior of the Pakistani clerics in the Pakistani delegation, who runs a large seminary in the port city of Karachi and is respected by several Taliban leaders.

``He has a lot of influence on the Taliban and is also well-respected by Mullah Mohammad Omar,'' an official of one Islamic party told Reuters.

``Several other of the clerics also have the status of a teacher in the eyes of the Taliban and carry a lot of respect,'' the official said.

The Taliban have refused to hand over bin Laden, citing a centuries-old Afghan tradition that insists on giving hospitality to all who request help -- even at risk to the host's life.

Instead, they have tried to persuade their guest to leave, and a Taliban official said on Thursday that the edict to that effect appeared to have been delivered.

``The message had to be sent through a messenger who probably took some time to find him,'' Information Minister Qudrutullah Jamal told Reuters.

``It's not like we can pick up the phone and talk to Osama, or fax a message to him,'' he said. ``He has no such facilities, so the message had to be sent through a messenger who probably took some time to find him.''

The Taliban had earlier reported that bin Laden was missing and officials of the puritanical movement that rules Afghanistan by strict Islamic tenets had said they were trying to deliver the fatwa, or edict, passed by the clerics.

Asked about bin Laden's reply to the order to leave, Jamal said no response had yet arrived. ``We don't know yet because the messenger hasn't returned.''

How Mullah Omar reacts to an appeal from some of the region's most respected Islamic leaders remains to be seen.

Despite his perilous position, he has responded defiantly so far by demanding evidence of bin Laden's involvement in the attacks on New York's World Trade Center and the Pentagon.

The normally reclusive Omar has been unusually vocal of late, suggesting his grip on the Taliban may not be as secure as it once was.

He has ordered all Afghans to return to their homes after the United Nations reported millions of people on the move, either trying to flee the country or at least the cities for the safety of the countryside.

He has told his people that anyone helping the United States would face the wrath of his holy warriors.

With Afghanistan facing a major humanitarian crisis, U.N. Secretary-General Kofi Annan appealed for $584 million in fresh emergency aid to cope with up to 7.5 million Afghans likely to suffer from hunger and displacement in coming months.