WANA, Pakistan - Top al-Qaida terrorists may have escaped a siege by thousands of Pakistani soldiers through several secret tunnels leading from mud fortresses to a dry mountain stream near the border with Afghanistan, a security chief said today.

The longest tunnel found so far was more than a mile long and led from the homes of two local men - Nek Mohammed and Sharif Khan - to a stream near the frontier, said Brig. Mahmood Shah, head of security for Pakistan's tribal regions.

Three senior officials have told AP that they believe al-Qaida's No. 2 man, Ayman al-Zawahri, may have been at the site, though the government has repeatedly said it does not know who is inside. President Gen. Pervez Musharraf said Thursday that a "high-value" target was likely involved.

The militants may have used the tunnel to escape during the disastrous first day of the operation on March 16, when at least 15 soldiers were killed in fierce fighting. Still, Lt. Gen. Safdar Hussain, the commander of the operation, said over the weekend that authorities believe an important terrorist remains inside, based on the level of resistance of the holdouts.

Pakistan's military said it was conducting DNA tests to identify six suspected foreign terrorists killed in the fighting, but would not elaborate on whether they included any important terror figure.

In Wana today, an 18-member tribal peace delegation crossed through a tight military cordon for talks with elders of the Yargul Khel tribe, believed to be fighting alongside the al-Qaida militants.

The delegation, carrying a white flag, was bringing three government demands: that the fighters free 12 soldiers and two government officials taken captive last week; that they hand over tribesmen involved in the fighting; and that they kick out any foreigners or show the military where to track them down.

Shah said that "in light of the past experience we are not very hopeful" the delegation would succeed.

Also today, Gen. John Abizaid, leader of the U.S. Central Command, was in Pakistan on an unannounced visit, Sultan said. He said a top army official met with Abizaid - who oversees U.S. forces in Afghanistan and Iraq - and insisted the trip had nothing to do with the

offensive in Wana.