Cotabato City, Philippines - Philippine troops and Muslim rebels clashed ahead of the signing of a controversial agreement on the expansion of a Muslim autonomous region in the country's troubled south, a military spokesman said Monday.

Lieutenant Colonel Romeo Brawner said the fighting erupted Sunday when Moro Islamic Liberation Front (MILF) rebels fired on an army encampment in Midsayap town in Cotabato province, 960 kilometres south of Manila.

Brawner said the rebels used high-powered weapons, including a 50-caliber machine gun, but there were no reported casualties on both sides as the soldiers repulsed the guerrillas.