Cacho said the freed men were handed over to the mayor's emissaries in the coastal township of Tuburan, about 50km from Al-Barka, where five soldiers were killed and more than 20 wounded in clashes with fighters on Sunday.

Targeting Abu Sayyaf

Philippine military chiefs say the operation is part of a campaign to "flush out" the Abu Sayyaf which is believed responsible for a series of kidnappings".

But Mohagher Iqbal, the chief negotiator for the Moro Islamic Liberation Front (MILF), a group fighting for a separate homeland for Filipino Muslims, told Al Jazeera on Monday that Abu Sayyaf members were not in the area and accused the military of trying to provoke a conflict with MILF forces.

"Three men from our forces were killed, and this was clearly a military offensive against our forces in Basilan," he said.

"The MILF is on defensive mode and the situation will escalate if the military do not stop these attacks," he warned.

Philippine military commanders say they believe that the Abu Sayyaf is being supported by the MILF.

The MILF formed as a breakaway group in 1977, when it split from the Moro National Liberation Front (MNLF). Following the split, the MNLF subsequently entered into negotiations with the government in Manila and signed an agreement a decade later relinquishing its stated goal of independence.

But the 12,000-strong MILF continues to fight for political autonomy and the group is one of four fighting for a separate Muslim state in the southern Philippines.

The Abu Sayyaf split from the MNLF in the early 1990s and US and Philippine intelligence agencies believe the group has ties to Osama bin Laden's al-Qaeda network.