MANILA, June 20 (Xinhua) -- Philippine troops clashed with suspected rebels in Sultan Kudarat province in the southern Philippines on Thursday, killing four, including one soldier, the military has said.

In a report, the military said the clash between patrolling soldiers and alleged New People's Army (NPA) rebels broke out before dawn Thursday.

"After two hours of fighting, the rebels retreated deep into the forest and left three of their companions with their three rifles," the report read.

The fierce gunfight resulted in the deaths of three insurgents at the clash site and the critical wounding of a soldier. The soldier succumbed to his injury at a local hospital.

NPA rebels have been fighting government troops since 1969. Military data showed that the NPA's personnel strength has declined since its peak of around 25,000 armed members in the 1980s.

Despite its dwindling fighters, the NPA continues to launch small-scale attacks in the countryside. ■