The clash was the second this month between the Moro Islamic Liberation Front (MILF), a separatist group negotiating with the government to end a long-running insurgency, and the breakaway Bangsamoro Islamic Freedom Movement.

Col. Manuel Ochotorena said 300 to 500 people had fled their homes in the heavily Muslim south of the mainly Roman Catholic country. They were unwilling to return for fear of renewed violence, particularly if the MILF starts pursuing the splinter group.

Television put the number of displaced at 700 in marshy areas by Saydona Mustapha town. Five people were wounded.

“They are afraid to return home because the two rival groups are still there and there could be fighting again,” Ochotorena said. “We hope they don’t bring the fighting to the highway because more people will be displaced.”

Peace talks have been held sporadically since 1997 but negotiations brokered by Malaysia stalled last month, with rebels demanding a “sub state” and rejecting a government proposal to boost powers of local authorities.

The splinter group rejects the peace process outright and vows to press on with a campaign for a separate and independent Islamic state on the island of Mindanao.

A MILF spokesman, Von al Haq, said the breakaway group had been given until Sept. 26 to disband or face attacks from both the main rebel force and government troops.

The splinter group’s leader was blamed for an outbreak of violence in 2008 after a deal between the government and the MILF was declared unconstitutional. He is wanted on charges of murder, arson and kidnapping.

The government has expressed concern that the breakaway group could torpedo the talks to end an insurgency that has killed 120,000 people, displaced 2 million and hindered growth in poor but resource-rich areas.