MILAWA, Afghanistan — Afghan fighters backed by U.S. aerial bombardment and special forces drove Osama bin Laden's remaining fighters onto a mountain ridge in eastern Afghanistan Friday, setting the stage for what could be their last stand.

Afghan commanders said they had routed the remnants of bin Laden's al-Qaida organization from most of the caves and other fortified positions they held in the White Mountains.

They said they were now trying to dislodge the al-Qaida fighters from the ridge and force them to lower ground without allowing them to escape through the mountains and across the nearby border with Pakistan.

The Afghan force of about 2,500 men claims to have seized most of al-Qaida's caves and bunkers in the Milawa and Tora Bora valleys. Zahir, a top commander and the son of the region's governor, said the ridge that the holdouts were defending "is their last position in Afghanistan." With that exception, he said, "the places we were aiming to capture, we captured all of them" in an offensive that began Thursday.

More than 300 al-Qaida fighters have surrendered to Afghan opposition forces in the mountains of eastern Afghanistan in recent days, adding to an estimated 5,000 to 6,000 terrorist or Taliban prisoners being held by rebel groups elsewhere in the country, U.S. officials said.

Briefing reporters en route from Washington to Central Asia, Defense Secretary Donald Rumsfeld said that the Afghans had advanced more than a mile and captured 50 more al-Qaida fighters during one eight-hour period of intense fighting. U.S. fighter jets and bombers dropped 180 bombs during that surge, and AC-130 gunships strafed al-Qaida positions, Rumsfeld said. Between 230 and 240 bombs, many weighing 2,000 pounds, were dropped on the same region the day before.

The prisoners being taken are part of what U.S. officials say is an expanding intelligence-gathering operation in Afghanistan in which U.S. Special Forces and CIA officers have also been examining seized al-Qaida documents, computer hard drives, videotapes and telephone books.

The material has already produced names and phone numbers of al-Qaida members in other countries and led to some additional arrests, according to senior administration officials.

Scientists from U.S. nuclear weapons laboratories have joined the military and CIA experts to assist searching the grounds of al-Qaida training camps for signs of actual work on chemical, biological or nuclear weapons, the officials said.

"So far," one senior official said, "no such materials have been found," though Rumsfeld said Thursday that some samples taken from the sites are still being examined in the United States.

The commander of U.S. operations in Afghanistan, Army Gen. Tommy Franks, said the Afghan forces are pushing the al-Qaida fighters from the north, while the Pakistani military has taken up positions blocking the border to the south. "It sort of becomes a hammer and an anvil," Franks said at a news conference in Tampa, Fla.

It remained unclear early Saturday whether bin Laden was among the al-Qaida holdouts, a contingent of Arabs and other foreign fighters estimated to number between 200 and 1,000. Hazrat Ali, the regional security chief in eastern Afghanistan, said he believed his forces had located the cave where bin Laden might be hiding and that they planned to clear and search the area.

Franks said that while intelligence information indicates bin Laden is still in the Tora Bora area, "at this point we simply don't know where he is." Franks also said the United States has plans for how to handle bin Laden if he is captured but declined to elaborate on them.

In Washington, President Bush urged patience in the hunt for the man accused of organizing the Sept. 11 terrorist attacks on New York and Washington. "I don't know whether we're going to get him tomorrow or a month from now or a year from now. . . . But we're going to get him," Bush said. "I don't care, dead or alive — either way. It doesn't matter to me."

In southern Afghanistan, Marines took control of the airport near Kandahar overnight and spent Friday searching for booby traps and land mines at the facility. Marine officials said they hope soon to have the airport, located about 12 miles southeast of Kandahar, in good enough shape to open it for humanitarian aid flights and, eventually, commercial traffic.

The Marines met no resistance when they drove through the city before dawn, but Friday afternoon flights in and out of the airport were suspended because of an unspecified threat to aircraft, Marine officials said.

The increasing presence of U.S. troops here in the White Mountains was amply evident Friday. More than 20 could be seen accompanying truckloads of Afghan fighters up the mountainside toward the front lines Friday, including one squeezed into a seat next to Ali, as their vehicle bounced over the rutted roadway toward the Afghans' command post.

Mohammad Ali, a 25-year-old fighter, said 12 Americans had accompanied his group of troops on Thursday. "They were coordinating," he said. "They had weapons but didn't fire."

One Afghan who participated in an overnight gun battle said at least five American military personnel were with each Afghan unit. "We asked them, 'Why did you come to this place?' " said Asad Yaah. "They said, 'To help you.' "

Afghan commanders said U.S. forces also were involved in combing through captured al-Qaida positions, including elaborate cave complexes and front-line bunkers.

Contributing: Walter Pincus and Bradley Graham, The Washington Post