American troops are on the ground in the Philippines preparing to expand a counterterrorism training program for the country's armed forces, the Pentagon said Thursday.

Some two dozen U.S. special forces are doing logistical and security planning for a larger force that could arrive within a week, said one defense official on condition of anonymity.

In Manila, Philippine armed forces spokesman Brig. Gen. Edilberto Adan said Wednesday that small groups of American soldiers, eventually totaling more than 100, soon would start arriving.

"We all know that the Philippine government has been very seriously attempting to deal with terrorists on one or two islands," Defense Secretary Donald H. Rumsfeld said Thursday, referring to the Abu Sayyaf extremist group.

"They have some hostages that have been taken over time, some of whom have been killed, some of whom, I believe, may have been released. But some are still held, including some Americans," Rumsfeld said at a Pentagon news conference.

Abu Sayyaf, believed allied to Usama bin Laden's Al Qaeda global terror network, has held hostage a U.S. missionary couple, Martin and Gracia Burnham, and Filipino nurse Deborah Yap for the past seven months Basilan island in the southern Philippines. It has beheaded some hostages and extorted large ransoms for others.

The U.S.-led training program is part of a larger package in which the United States also will provide warplanes, debt relief and trade assistance, conditions agreed in a November meeting between President Bush and Philippine President Gloria Macapagal Arroyo.

Gen. Diomedio Villanueva, Philippines' military chief of staff, said Wednesday that U.S. military advisers will be allowed to join front-line Filipino troops fighting Muslim guerrillas linked to Al Qaeda but not engage the guerrillas in combat.

His statement was the first by a senior Philippine military official that U.S. forces would be allowed in battle areas. Previously, visiting U.S. experts in special operations have stayed in army camps. Under Philippine law, foreign troops are not allowed to engage in combat in the islands.

The new assistance approved since the Sept. 11 attacks on America expands U.S. efforts dating back to 1993 to help the Philippines fight terrorism. The Moro Islamic Liberation Front, formerly the Moro National Liberation Front, began fighting in the early 1970s for a Muslim state in the overwhelmingly Roman Catholic country.

"Our belief is that the Philippine armed forces, when properly trained, equipped and assisted, are able to take on the war on terrorism in the southern Philippines on their own," said Lt. Cmdr. Jeff Davis, a Pentagon spokesman.

Philippine spokesman Adan has said U.S. experts will provide training, assistance and advice on subjects including psychological warfare, intelligence and night flying.

Since the November agreement was signed, the Philippines has received equipment including a C-130 transport plane, eight Huey helicopters and 30,000 rifles, the Pentagon says.

Officials are expecting a patrol boat in the coming months.