Tensions are high in Jolo as the fighting continues

More than 2,000 soldiers are now in the area fighting several hundred men from the Abu Sayyaf, which has been tied to al-Qaeda, and a rebel splinter group.

More than 60 people have been killed since the clashes began, in some of the most intense fighting for years.

Thousands of villagers have arrived in Jolo town to escape the violence.

There have been some calls from local leaders for a ceasefire, but a military commander in the region, Lt Gen Alberto Braganza, appeared to rule out the idea.

"I have a mission to accomplish on the ground, I will finish what the rebels started," he said.

Guide to Philippine conflict

The fighting began on Monday and appears to have been triggered by the army's entry into rebel territory following an ambush.

The rebels are believed to include fighters from the Abu Sayyaf and some disgruntled members of the Moro National Liberation Front (MNLF), which signed a peace deal with the government in 1996.

The Philippines government said on Friday that the MNLF fighters were being led by a brother of Nur Misuari, who used to lead the MNLF until he was jailed on charges of rebellion in 2001.

There has been no sign yet that a larger rebel group, the Mindanao-based Moro Islamic Liberation Front (MILF), will become involved in the dispute or end its ceasefire.