Taliban fighters and members of Usama bin Laden's Al Qaeda militia were putting up fierce resistance against opposition Afghan forces outside Kandahar on Tuesday as a relentless U.S. bombing campaign continued, tribal leaders said.

Some Kandahar defenders fired missiles at U.S. warplanes, but made no hits, U.S. officials said.

The city, the last bastion of the Taliban, remained in the hands of the Islamic group, but a seesawing battle was raging for its airport, a few miles away. A senior ethnic Pashtun leader made new surrender demands on Taliban supreme leader Mullah Mohammed Omar, who has ordered his forces to fight to the death.

Abdul Jabbar, an Afghan tribal representative in Pakistan in contact with commanders at the scene, described the fighting as close combat. "They're face-to-face," he said.

After days of clashes, Pashtun tribal fighters loyal to former Kandahar governor Gul Agha battled their way into Kandahar airport from the south on Tuesday despite fighting by pro-bin Laden Arab fighters, said one tribal commander, Mohammed Jalal Khan.

He said tribal warriors had captured half of the airport and were fighting for control of the terminal building.

Other troops loyal to former deputy foreign minister Hamid Karzai were advancing on Kandahar from the north.

The Taliban claimed to have repelled an assault by Karzai's troops in heavy fighting that they said left dozens of anti-Taliban fighters dead or wounded, the Pakistan-based news service, Afghan Islamic Press, reported.

But Abdul Malik, a spokesman for Karzai in Quetta, Pakistan, denied there was any fighting, saying Karzai's troops had advanced peacefully to within 18 miles of the city.

He said Karzai had dispatched a new delegation to Kandahar to demand the Taliban's capitulation.

"We don't want any more dead, above all now that it's clear that the Taliban have lost," the Rome daily newspaper, La Repubblica, reported Karzai as saying. "Mullah Omar must understand, and this is the message we are sending him, he must surrender, he must recognize that the battle is over."

Mullah Omar, believed to be holding out in Kandahar, has ordered troops to defend the city to the death and not retreat as they did when other cities were besieged by anti-Taliban forces.

Reports from either side could not be verified as the Taliban have barred western journalists from the region. Karzai is being touted as a possible interim national leader in a proposed broad-based temporary administration for Afghanistan.

A contingent of more than 1,000 U.S. Marines at a base about 70 miles southwest of Kandahar has been conducting armed reconnaissance patrols, but has stayed out of the fighting.