The American and Philippine governments agreed to an arrangement that will place U.S. troops in direct combat roles against the Abu Sayyaf for the first time since the U.S. military began advising the Philippine armed forces in counterterrorism tactics last year, the officials said. The deal marks a major escalation of U.S. military involvement in the Philippines. 

About 350 U.S. special operations forces, mostly Army Green Berets, will be involved in the offensive in the Sulu Archipelago, with much of the effort focused on the island of Jolo, the officials said, speaking on condition of anonymity. 

It was not immediately clear how many Philippine forces would be involved in the offensive. 

In addition to the U.S. special operations forces and the support personnel, a team of about 1,000 Marines aboard Navy ships off the coast of the Sulu Archipelago will be available to respond on short notice with air power, logistics help and medical aid. 

The Marines are part of the Okinawa-based 31st Marine Expeditionary Unit, and their lead ship is the USS Essex, based at Sasebo, Japan. 

U.S. officials have said in recent days that they have new information showing a stronger link than previously believed between the Philippine rebels and other international terrorist groups. 

The government of Philippine President Gloria Macapagal Arroyo said Monday that she had approved joint training with U.S. forces on Jolo, where some Abu Sayyaf rebels fled after the previous U.S.-Filippino effort last year to root them out of Basilan island, to the north of Jolo.

U.S. officials said the next offensive, to begin sometime in March at the Philippine government's choice, would go well beyond training to include direct combat roles for U.S. forces. 

The purpose, one official said, is to "disrupt and defeat the Abu Sayyaf group." He said the effort had not time limit and would continue as long as both governments agree it is needed. 

There are believed to be several hundred Abu Sayyaf rebels in the Philippines. Early this month the Philippine military announced it had greatly underestimated the number of Abu Sayyaf and warned it would take a long time to wipe them out. 

A Department of National Defense report submitted to the Philippine Congress late last year placed their strength at 250, down from 800 in 2001. But Chief of Staff Gen. Dionisio Santiago acknowledged Feb. 5 that a recheck of military documents and figures showed a number closer to 500 - most on the impoverished island of Jolo. 

Several terrorist groups, some with suspected links to al-Qaida such as the Islamic extremist network Jemaah Islamiyah, operate in the Philippines and there have been a series of deadly bombings, kidnappings and other attacks against both government and civilian targets. An Oct. 2 incident blamed on Abu Sayyaf killed three people, including a U.S. Green Beret in the port city of Zamboanga. 

Pentagon officials say investigations following some of those attacks have turned up information indicating there may be a stronger than earlier believed link between the Abu Sayyaf and the Jemaah Islamiyah of Indonesia.