A Philippine army officer says suspected communist guerrillas have killed four unarmed, off-duty soldiers who were traveling on motorcycles on the way back to camp from a public market in the south.

Maj. Rosa Maria Cristina Manuel says about 10 New People's Army rebels opened fire with M16 rifles on the soldiers in the rural outskirts of Davao city late Sunday afternoon, initially killing three soldiers along a dirt road.

Manuel told The Associated Press by telephone on Monday that the rebels dragged another soldier to a rice field and fatally shot him. Troops found his body Monday.

The 43-year Marxist rebellion, one of Asia's longest-running, has left more than 120,000 people dead and held back progress in poverty-wracked rural regions in the country.