Philippine communist guerrillas are marking the 50th anniversary of their rural rebellion with threats of more attacks, possibly in cities, as a negotiated settlement remains elusive and peace talks have repeatedly stalled.

The New People's Army marked its 50th year on Friday with an attack on a police patrol in northern Mountain Province that killed a policeman. Authorities say a separate rebel assault on an eastern provincial police station on Thursday backfired when officers fought back and killed three insurgents.

The Communist Party of the Philippines said its rebel wing should be strengthened "several times over" and carry out assaults "to punish the enemy in the cities."

The Department of National Defense vowed to make the rebels "strategically irrelevant" within three years.