Army Col. Cesar Idio said the government troops killed four rebels in the ambush in Masbate's Cawayan township on Monday. A soldier was killed and three others were slightly wounded.
Additional forces and armored military vehicles were deployed following the clash, he said.
The troops were ambushed while on their way back to headquarters after arresting two rebels earlier in the day.
The Marxist insurgency has flared on and off for 46 years, one of the longest-running rebellions in Asia, but authorities say the insurgency has been considerably weakened in recent months in the northeastern Bicol region.
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