U.S. Marines helping search for leaders of Afghanistan's Taliban militia and the Al Qaeda terror network found documents, guns and other items that could be useful, defense officials say.

Starting Monday, about 200 Marines searched a 14-building compound west of Kandahar for 29 hours, the Pentagon said.

The operation was part of U.S. efforts to eradicate the Al Qaeda network and locate former Taliban rulers who went underground after the fall of Kandahar, their final stronghold. Officials said Wednesday it was not specifically an effort to capture Taliban leader Mullah Mohammed Omar or Usama bin Laden, the alleged Al Qaeda mastermind.

"To say that we have U.S. forces that are specifically ... going to look for these two individuals wouldn't be correct," Rear Adm. John Stufflebeem told a Pentagon news conference.

Instead, he said, American forces sought evidence that may eventually lead to the capture of Omar and bin Laden.

"We're casting a relatively wide net to build intelligence," said Stufflebeem, deputy director of operations for the Joint Chiefs of Staff.

Other U.S. officials, speaking on condition of anonymity, said the intelligence value of the materials found appeared to be modest.

American forces also are searching for clues in caves in the Tora Bora area of northeastern Afghanistan. Al Qaeda fighters fled from there last month after weeks of relentless U.S. aerial attacks. Some believe that bin Laden has been in Tora Bora, but Stufflebeem said his current location is a mystery.

Small groups of surviving Al Qaeda members appear to be trying to regroup, Stufflebeem said.

As evidence of that, he cited a U.S. airstrike last Friday on what he described as a military compound north of the city of Gardez, in eastern Afghanistan. He did not elaborate but implied that the compound was struck because it was believed to contain Al Qaeda fighters.

"The job here is to get rid of Al Qaeda," Stufflebeem said. "But it's also a global job. And so we also have got this net cast around the world to find out where Al Qaeda is or may be going to."

Taliban forces in Baghran, northwest of Kandahar, are negotiating with members of the interim Afghan government led by Hamid Karzai on terms for their surrender, Stufflebeem said. He estimated they number 1,000 to 1,500 and said it would be a "leap of faith" to believe the surrender talks are being conducted on behalf of Omar.

"These are Taliban forces that are looking to negotiate themselves out of a predicament with anti-Taliban forces," he said.

Victoria Clarke, chief spokeswoman for Defense Secretary Donald H. Rumsfeld, said that surrender negotiations does not mean the U.S. military campaign is pausing or slowing.

"We intend to prosecute this in a very vigorous fashion," she said at the news conference with Stufflebeem.

Col. John Mulholland, commander of U.S. special operations forces in Afghanistan, told a small group of American journalists in the region Wednesday that bin Laden could be dead or trapped under rubble in the Tora Bora area. If bin Laden survived the U.S. bombing, Mulholland said, he probably has fled.

"I don't think he's up there," Mulholland said.

In other developments, Clarke said about 200 members of the Army's 101st Airborne Division arrived at Kandahar airport. The Army soldiers are the vanguard of a larger force that will replace the approximately 1,000 Marines who have been securing the airport and building a detention facility.

Also, the Pentagon said the crash of a Global Hawk unmanned spy plane Sunday was being investigated as an accident. The aircraft crashed in a country near Afghanistan, but Stufflebeem refused to identify the country. The U.S. Central Command said Wednesday the wreckage had been recovered.

The crash apparently happened because of poor maintenance, Stufflebeem said. "Clearly," he said, "it was not shot down."