U.S. officials are interrogating prisoners, scrutinizing surveillance photos and asking for help from friendly forces in trying to track down top Taliban and Al Qaeda leaders who have disappeared in Afghanistan.

Among the prisoners the Americans are questioning are two senior Taliban officials being held on a U.S. warship off the coast of Pakistan, defense officials said Wednesday.

Interrogations of the scores of Usama bin Laden loyalists captured in Pakistan should yield a "treasure trove" of leads for the U.S. campaign to hunt down the missing terrorist leader and eradicate his Al Qaeda network, Defense Secretary Donald H. Rumsfeld said.

He said U.S. forces are helping anti-Taliban Afghans clear caves "one by one" in the Tora Bora area, the last bastion of the Al Qaeda before the group largely abandoned the area Monday. He said the work is slow and difficult, complicated by bad weather and darkness.

The top Taliban officials are among five prisoners being held aboard the USS Peleliu in the Arabian Sea, said defense officials speaking on condition of anonymity. Of the other three, one is John Walker, the American who fought with the Taliban, one is an Australian associated with the Taliban and one is a Saudi Arabian member of a group accused of having terrorist ties.

The officials did not know the names of the two Taliban officials or their positions. The militia ruled Afghanistan for five years until its collapse this month.

FBI agents familiar with the Sept. 11 terrorist attacks also have arrived at a U.S. Marine base in Afghanistan to help interrogate prisoners there.

Some of the most pressing questions for all the prisoners concern the whereabouts of leaders such as bin Laden and Mullah Mohammed Omar, the head of the Taliban.

Rumsfeld said he did not know how many of the prisoners held by the Pakistanis are senior Al Qaeda figures. He said they number in the hundreds, although Pakistan on Wednesday put the figure at 156.

"If they're Al Qaeda ... you can be darned certain we're going to try to get our hands on them," Rumsfeld said.

"Clearly we will be involved in interrogations and intelligence gathering because it should be a treasure trove," he added.

U.S. experts also will be poring over photos, videos and other surveillance information gathered by satellites, planes and helicopters over Afghanistan and Pakistan. Rumsfeld said at a Pentagon news conference that the United States has airborne reconnaissance watching the area, but did not elaborate.

Several types of "eyes in the sky" probably are involved. Satellites can take high-resolution pictures of the ground, intercept radio and mobile telephone communications and take radar images. High-flying planes like the U-2 and the unmanned, remote-controlled Global Hawk can take pictures as well.

U.S. helicopters have been flying over the mountainous Afghanistan-Pakistan border at night, likely using night-vision equipment to try to spot people, pack animals and vehicles in the darkness.

Attack jets such as F/A-18s also have night-vision equipment and can immediately fire on enemy troops and positions. Even the unmanned Predator reconnaissance drones can be fitted with anti-tank Hellfire missiles.

More than 100 Al Qaeda fighters have been arrested by Pakistani authorities after fleeing from Afghanistan's Tora Bora region this week, and others are being hunted day and night by Afghan and U.S. forces. But Rumsfeld said it was a mistake to declare Al Qaeda defeated.

"They certainly aren't functioning well," he said. "They're running, and they're hiding, and they're having difficulty communicating with each other, but a large number of them seem to behave in a fanatical way, and I suspect that we'll hear more of them."