Dozens of fighters loyal to Usama bin Laden, arrested as they crossed the border from Afghanistan, rose up against their Pakistani guards Wednesday, seized weapons and escaped. Seven Al Qaeda fighters and six police were killed, officials said. 

After a brief and bloody gunbattle in the morning, Pakistani tribal forces and army helicopter gunships pursued the fugitives, capturing 21. As night fell, they were searching for 20 more in the mountainous border region, officials said. 

The Al Qaeda fighters — mostly Arabs — were from among 156 arrested over the past two days as they came across the border, the government of Northwest Frontier Province said in a statement. Just on the other side of the frontier, Afghan forces backed by U.S. airstrikes drove Al Qaeda followers from their mountain base in Tora Bora in recent days, sending many fleeing into Pakistan. 

Hundreds of Al Qaeda — including some top commanders — were allowed to escape by commanders in the Afghan eastern alliance that led the assault on Tora Bora, an alliance official said. Two alliance commanders have been rebuked for conniving to let bin Laden followers flee into Pakistan, the official said. 

In Tora Bora, the search continued for remaining Al Qaeda members or clues to the whereabouts of bin Laden. U.S. helicopters ran night missions through the mountain valleys, while Afghan fighters brought more prisoners and documents from a sweep of snow-laden cave hide-outs. 

The prisoner revolt took place near the northwestern Pakistani town of Parachinar. The prisoners, held in the town overnight, were being transferred in a convoy of buses and trucks to a larger facility, the provincial government said. 

"One of the Arabs shouted 'Allahu Akbar!' [Arabic for "God is great"] and with that slogan, the others attacked," bus driver Rehman Ali told The Associated Press. He said they seized guns from the six guards on the bus and shot them dead. Three prisoners were killed in the struggle. 

Ali said the prisoners tried to drive the bus away, but lost control and it overturned. The fighters poured out and engaged security guards from the other buses in a firefight, he said. Three more prisoners were killed and one was wounded, and seven police were wounded, he said. 

The provincial government said a total of seven Arabs and six security officials were killed. Their reports could not be reconciled. The government said 48 Al Qaeda men were on the bus. 

Tribal security officials and soldiers went after them, using ground troops and helicopter gunships, catching 21, and throwing a security cordon over the area to search for the rest, the provincial government said. 

Last month, Al Qaeda forces in northern Afghanistan revolted the day after their capture, sparking a three-day battle at the fortress near Mazar-e-Sharif where they were being held. A CIA operative, Johnny "Mike" Spann was killed, as were dozens of guards and hundreds of prisoners. 

Pakistan has poured helicopters and thousands of soldiers into the tribal areas along the border and set up 300 checkpoints to cut off escape routes from Tora Bora. Pakistan earlier said it had arrested at least 108 fighters fleeing the area, including at least 60 Arabs and other non-Afghans. 

International forces were preparing to take positions in Afghanistan's capital, Kabul, in time for the inauguration Saturday of a six-month interim government. Military advisers from 17 countries that have offered to contribute peacekeepers were meeting in London to nail down details. 

The U.N. Security Council was poised to approve the force, possibly by Thursday, after key council members agreed the troops would be authorized to use military force if necessary. A vanguard of 200 British soldiers could move from Bagram airport to Kabul, at the head of a force that could grow to number 3,000 to 5,000. 

The appointed Afghan leader, Hamid Karzai, said Wednesday bin Laden should be turned over international justice, if caught — a call echoed by the top U.N. war crimes prosecutor. But the United States insisted it must try the man wanted for the Sept. 11 terror attacks. 

"A man like that who has committed crimes worldwide must be given to international justice," Karzai said in Rome after receiving the blessing of the 87-year-old former Afghan King Mohammad Zaher Shah. 

In Tora Bora, the whereabouts of bin Laden remained a mystery, as the capture of more of his followers brought new rumors. 

An Afghan alliance commander said a few non-Afghan fighters were captured overnight without resistance, and more stragglers were expected to surrender as the weather turns colder and the snow deepens. 

Some captives "are telling us stories about Usama giving a speech 14 days ago and then leaving, but these men are not very credible," Afta Gul, a commander of the eastern tribal forces, said. "I have heard that Usama has shaved his beard and gone to Pakistan, but no one can say for sure." 

Hulking black U.S. helicopters took off repeatedly after dark Tuesday and before dawn Wednesday, flying without lights up the valley leading to the warren of caves. The special forces troops assigned to comb the area refused to speak to reporters. 

B-52 bombers and EP3 Orion reconnaissance aircraft droned overhead, but no ordnance was dropped. 

Afghan fighters returned to their base with piles of maps and Arabic-language documents from caves they searched Tuesday, including a topographical map marking mortar positions and their field of fire, and a training manual on aiming tank fire. 

Meanwhile, a top alliance official said the eastern alliance's governing council, or shura, met in Jalalabad on Friday and rebuked two senior tribal leaders who some shura members accused of helping Al Qaeda fighters flee Tora Bora. 

Hundreds of Al Qaeda family members escaped, and top Al Qaeda commanders may have been among them, said the offical, who attended the meeting and spoke on condition of anonymity for fear of retribution. 

Pakistan dismissed allegations that its authorities also protected Al Qaeda fugitives. 

At a U.S. Marine base at Kandahar airport in southern Afghanistan, FBI agents prepared to question 15 Al Qaeda and Taliban captives. 

FBI agent Thomas K. Knowles said none of the 15 were among the 22 on the U.S. list of most wanted terrorists. "They are young fighters," he said. "We are still trying to figure out who we want to talk to, who has information." 

Deputy Defense Secretary Paul Wolfowitz has said the 15 were picked for questioning out of thousands held by Afghan forces because they are suspected of having "important information and might be themselves senior people." 

Five more captives were being interrogated on board the USS Peleliu, including an American and an Australian who fought with the Taliban. The other three were either Taliban or Al Qaeda. 

One was believed to be Abdul Aziz, a Saudi Arabian official of the Wafa humanitarian organization, a U.S. official said on condition of anonymity. The group's assets have been frozen by the Bush administration for alleged terrorist ties.