By Sarah Toms
BBC News, Manila
Security forces in the southern Philippines say two commandos have been killed and 17 wounded in fresh clashes with Muslim militants.
Troops are searching for several key militants
Fierce fighting broke out again on the remote island of Jolo as the army tried to flush out rebel leaders.
The military sent a battalion of army rangers to Jolo on Monday to bolster 3,000 troops already hunting some 200 members of the Abu Sayyaf group.
The military says the rebels also suffered a number of casualties.
Security forces say these fresh clashes first erupted on Tuesday when soldiers ran into a group of rebels.
Troops had begun combing the jungles this week after the militants slipped through a dragnet around the mountains near Indanan town.
The latest army offensive is targeting Khadaffy Janjalani, the leader of the Abu Sayyaf group.
Abu Sayyaf is the smallest of four Muslim rebel groups in the Philippines with aBOUT 400 members.
It is blamed for kidnappings and bombings, including an attack on a ferry in 2004 that killed more than 100 people.
The campaign also aims to capture the two main suspects in the 2002 Bali bombings, Dulmatin and Umar Patek, who are believed to be hiding in the Philippines.
The two Indonesians belong to Jemaah Islamiah, or JI, a regional Islamic network with alleged links to al-Qaeda.
Despite numerous campaigns on Jolo, Abu Sayyaf leaders and foreign militants have eluded capture.
This time the military is confident of success because it says the rebels no longer enjoy the support of villagers who have suffered years of conflict.