ZAMBOANGA, Philippines - Security forces in the Philippines were bracing themselves for further attacks by Islamist militants after fierce clashes claimed 32 lives, the military said Tuesday.

The two days of fighting on Jolo island, a stronghold of the Al-Qaeda-linked Abu Sayyaf group, was the second major battle between the two sides in less than a month.

"We are on a heightened alert now. We have intelligence reports that the Abu Sayyaf is going to attack (the capital town of Jolo)," said Chief Inspector Usman Pingay, head of the town police.

"We have checkpoints and roadblocks and we have additional foot patrols for security."

Jolo town, with a population of 140,300, is close to the captured Abu Sayyaf camp.

The Abu Sayyaf fighters had scattered after the fall of their camp following fighting on Sunday in which the military bombed their hideout.

Communities on the island expressed fear of militant attacks, with people living near military camps fleeing their homes.

The military claimed a big victory in over-running the Abu Sayyaf camp outside Jolo town, saying 19 extremists were believed to have been killed and that it had significantly hurt the group's operations on the island.

But a day later, the Abu Sayyaf ambushed Marines who had just left the newly captured camp, killing eight soldiers while losing five more of their own fighters, according to the military.

Military spokesman Major Ramon David Hontiveros said troops only overran the rebel camp after learning that 220 Abu Sayyaf fighters were massing there, possibly for an attack on nearby Jolo town.

"We perceived this as a threat to the capital of Jolo. The presence of 200-plus Abu Sayyaf necessitated action by the armed forces," he told AFP.

Regional military chief Major General Benjamin Dolorfino said the fallen camp was a "typical" Abu Sayyaf hideout consisting of thatched huts and shallow trenches leading to small bunkers.

Its capture "is significant because this is their main stronghold," where they could take refuge, shielded by the presence of other Muslim armed groups, Dolorfino said.

However Hontiveros warned that the fall of the camp did not mean an end to the violence.

"The capture of that camp is a good outcome but... it takes a lot more than taking one camp. We need to locate them again to prevent them mounting more attacks," he said.

The Abu Sayyaf was established in the early 1990s, allegedly with seed money from Osama bin Laden's Al-Qaeda network, to fight for a Muslim state in the south of this mainly Roman Catholic nation.

It has kidnapped dozens of foreign aid workers, missionaries and tourists and was blamed for the country's worst terrorist strike, the bombing of a ferry in 2004 that killed more than 100 people.

The latest fighting came after a battle between troops and the Abu Sayyaf left 43 dead on the nearby island of Basilan in August.

The Abu Sayyaf relies mainly on extensive family relations to survive and thrive on the small island of Jolo, where small units of US military advisers are training Philippine counter-terrorist forces.