TORA BORA, Afghanistan – Afghan tribal fighters overran some cave and tunnel complexes in this suspected refuge of Osama bin Laden yesterday and gave al-Qaida holdouts an ultimatum to surrender or face annihilation. There was no word if bin Laden was among them.

Eastern alliance fighters swarmed over abandoned al-Qaida positions after devastating U.S. airstrikes, which included 15,000-pound “daisy cutter” bombs that flattened hillsides and scattered debris over the barren, wind-swept hills.

Hundreds of bin Laden’s foreign fighters tried to escape but were trapped by shelling in a rocky canyon. Some contacted tribal commanders by radio and pleaded for the chance to give up.

Mohammed Zaman, defense chief for the tribal eastern alliance, gave al-Qaida until 8 a.m. Wednesday (10:30 p.m. EST yesterday) to surrender or face a new attack.

Zaman agreed to a pause in the fighting after a radio conversation with al-Qaida fighters in the Pashtun language, monitored in part by an interpreter working for The Associated Press.

Afterward, he met some al-Qaida commanders whom he said begged him: “Please don’t fight us, we want to surrender.” Still, Zaman said he was skeptical all fighters would give up peacefully.

Pentagon officials said the war against terrorism was far from over and that some al-Qaida members might be hiding in the underground network of caves and tunnels. Defense Secretary Donald H. Rumsfeld warned that there might be holdouts willing to fight, saying, “a wounded animal can be dangerous.”

Gen. Richard B. Myers, chairman of the Joint Chiefs of Staff, said in Washington that there were “literally thousands” of caves in the Tora Bora area. He said American troops entered some caves, but he did not know if they had been used by al-Qaida.

Myers described Tora Bora, located in the towering White Mountains of eastern Afghanistan along the border with Pakistan, as “the last effective al-Qaida stronghold.”

Meanwhile, in southern Afghanistan, U.S. Marines patrolled roads leading from the fallen Taliban city of Kandahar, searching for Taliban and al-Qaida fugitives. Marine spokesman Capt. David Romley said low-ranking Taliban soldiers from Afghanistan who surrender their arms will be allowed to go free, but those who refuse will be killed.

The whereabouts of bin Laden, who U.S. officials suspected was in Tora Bora, remained unclear. One tribal commander claimed scouts spotted the Saudi exile with al-Qaida troops in the area Monday.

Deputy Defense Secretary Paul Wolfowitz said the best indications point to bin Laden’s presence in the area, but he admitted the reports are “not very reliable.”

Yesterday’s advance on Tora Bora occurred three months after the Sept. 11 terrorist attacks, which the United States blames on bin Laden. President Bush launched airstrikes on Afghanistan on Oct. 7 after the former ruling Taliban refused to hand over bin Laden.

In other developments:

U.N. special envoy Lakhdar Brahimi met leaders of rival Afghan factions in the Afghan capital, Kabul, and said an interim administration under Pashtun tribal leader Hamid Karzai was on track for its planned Dec. 22 inauguration. Secretary of State Colin Powell said Britain will take the lead role in overseeing the peacekeeping force for Afghanistan. A U.S. federal grand jury issued the first indictment directly related to the Sept. 11 attacks. Zacarias Moussaoui, a French Moroccan who is in custody, was charged with six counts, four punishable by death. The Red Cross said yesterday it was investigating reports that dozens of Taliban captives suffocated in shipping containers while being taken to prison in northern Afghanistan. The United States said James F. Dobbins, the U.S. diplomat who steered rival Afghan factions into an interim government, will reopen the U.S. Embassy in Kabul. The new governor of Kandahar, Gul Agha, said his militiamen would begin scouring the countryside for Taliban as soon as he restores order in the city, which the Taliban fled Friday. At Tora Bora, Afghan fighters cautiously peered into the caves that had been abandoned by al-Qaida and entered some only as far as sunlight extended, fearing boody traps or hidden enemy fighters.

It was unclear how much of the cave complex at Tora Bora had been captured.

Hazrat Ali, a senior commander with the eastern alliance, said fleeing al-Qaida troops had been trying to head south to escape into Pakistan, where intelligence officials said 4,000 troops had blocked all possible escape routes along a 25-mile stretch of border in the White Mountains.

Eastern alliance forces launched a three-pronged assault Monday against al-Qaida defenders at Tora Bora.

Shelling and machine-gun fire echoed across the valleys as B-52s and U.S. surveillance aircraft circled above. Afghan troops said dozens of heavily armed U.S. soldiers were seen headed to the front late Monday. After a night of heavy gunfire, the Americans returned before dawn yesterday to a camp in the nearby village of Pacir.

Gen. Tommy Franks, the U.S. commander of the war, sent at least several Air Force AC-130 gunships to the Tora Bora area to team with Predator unmanned surveillance planes, U.S. officials said. Predators can feed live pictures of ground activity to the gunships, which are capable of unleashing devastating attacks on ground targets with their 40mm cannon, 105mm howitzer, and 25mm Gatling gun.

Reporters who followed the fighters saw evidence of the devastation caused by the bombing. A sniper nest on top of a ridge contained three dead al-Qaida fighters, their bodies shredded by heavy machine gun fire.

Outside an al-Qaida firing range, paper targets from the National Rifle Association littered the ground complete with names of the trainees and their scores written in Arabic.

The al-Qaida hide-outs at Tora Bora are a vast complex of natural caves fortified by concrete and steel, which could be difficult for bombs dropped by air to destroy, according to Jack Shroder, a professor of geology at the University of Nebraska and an expert on Afghan caves.

The bunkers were originally built by Afghans, with help by Americans, during the war against Soviet troops and more recently were fortified by al-Qaida, Shroder said yesterday.

The caves also have numerous exits and entrances that could be camouflaged. “I bet there are a lot of those and we don’t know where they are,” he said.