There was "intense fighting" early today between soldiers and the Bangsamoro Islamic Freedom Movement in North Cotabato province's Aleosan township, said Col Dickson Hermoso of the army's 6th Infantry Division.
The rebel group set off a roadside bomb Wednesday in nearby Maguindanao province, wounding seven soldiers, and warned of more attacks. It broke away from the Moro Islamic Liberation Front, which has signed a preliminary peace accord with the government.
Provincial Gov Emmylou Mendoza said about 2,000 people fled their homes to avoid being caught in the fighting.
A similar offensive was launched earlier against the al-Qaida-linked Abu Sayyaf in Basilan province farther south to stop the militants from manufacturing bombs for attacks in other southern cities.
At least one soldier and an estimated seven militants were killed in the fighting in Basilan on Thursday.