The death toll included 25 soldiers and 27 militants killed Thursday when suspected Abu Sayyaf extremists ambushed a truck carrying troops headed to get supplies, then fought a running gunbattle with soldiers in pursuit, said Lt. Col. Bartolome Bacarro, the military's spokesman.
"As far as I can remember, this is our biggest casualty in a day," Bacarro told reporters.
Ten soldiers and 25 militants were wounded in Thursday's clashes, he added.
"We are not going give up because we have suffered casualties," military Chief of Staff Gen. Hermogenes Esperon said. "These are the people who have been beheading people ... and so we want to go after them even at the expense of the lives of our soldiers because that is our duty."
He said President Gloria Macapagal Arroyo, was "very concerned" about the number of government casualties and directed the military to review its operational policies in the battlefield.