The fighting occurred in four remote villages near the southern city of Malaybalay, a military statement said, at the start of a two-day unilateral Christmas truce declared by the Philippines' communist party and its armed wing, the New People's Army (NPA).

The military's Fourth Infantry Division did not immediately release details of the Malaybalay clashes that it said left nine NPA rebels dead.

President Ferdinand Marcos's government and the rebels announced last month that they intend to resume peace talks next year, following a series of failed negotiations launched by previous governments since the ouster of Marcos's father, the late dictator, in 1986.

The Maoist insurgency, one of the world's longest-running, has claimed thousands of lives.

The rebels had announced on Saturday that they would observe a two-day "suspension of tactical offensives" from Christmas Day to mark the insurgency's 55th founding anniversary on Tuesday.

The military had said it would not observe a Christmas ceasefire this year with the NPA, which it said has less than 2,000 members left after a high of around 26,000 guerrillas in the 1980s.