Manila: Philippine communist rebels on Friday vowed to step up attacks on mine site, plantations and logging companies they say were detrimental to people's interests.

The New People's Army (NPA) also threatened to intensify "tactical offensives" on military and police units to stock up on weapons.

On Friday, the police went on full alert, anticipating rebel attacks to mark the NPA anniversary.

"Certain enterprises and certain installations are targeted by the NPA because these are detrimental to the interests of the people,'' the NPA said in a statement.

Since the start of the year, NPA rebels have attacked at least three mining sites on the southern island of Mindanao and on Masbate island.