At least 40 militants and four soldiers were killed as the Philippine Army continued its all-out offensive in the province of Maguindanao, a military officer said on Monday.
The militants belonged to the Bangsamoro Islamic Freedom Fighters (BIFF) terror group, Xinhua reported.
The offensive against the militant group took place around the borders of Mamasapano, Datu Piang and Shariff Saydona Mustapha towns, the officer said.
Four Philippine Army soldiers of the 33rd Infantry Battalion were killed.
Troops have recovered one M-60 machine gun, two M14 rifles, a grenade, two pairs of binoculars and assorted ammunition from the militants.
The BIFF is the armed wing of the Bangsamoro Islamic Freedom Movement, the largest Muslim rebel force in the Philippines.