The slain Army officer was 2nd Lt. Raymond Hernandez, while the four soldiers remained unidentified.
Army Col. Roland Detabali said Hernandez and his men were on patrol in Sitio Tugas, Barangay Kanjamak at around 7:30 a.m. when their jeep hit a land mine, causing the vehicle to overturn and throw them to the ground.
The bandits and MNLF fighters then opened fire on the soldiers, killing Hernandez and his four men, Detabali reported.
He said the other soldiers were able to return fire, hitting a number of the attackers who were forced to retreat to the jungle.
It was not immediately known how many bandits were wounded, but the soldiers believe there were many casualties because they found bloodstains at the scene, he added.
Detabali said the attack was staged by bandits believed to be followers of Radullah Sahiron a gangmate of the Abu Sayyafs Ghalib Andang, alias Commander Robot and former governor Nur Misuari of the Autonomous Region in Muslim Mindanao.
Andang led Abu Sayyaf bandits in snatching 21 mostly foreign tourists from an island resort off Sabah on Easter Sunday almost two years ago, he added.
Detabali said Hernandez and the four slain soldiers belonged to the Armys 59th Infantry Battalion. Roel Pareño