MANILA, Dec. 10 (Xinhuanet) -- The Philippine rebel New People's Army was blamed for the two ambush attacks Thursday that killed five policemen and a security guard, the police said Friday.

    Three policemen were shot dead on Thursday afternoon while responding to a call about an alleged bomb in Silang town, Cavite in the northern Philippines, a police report said.

    Later on Thursday night, unidentified men sprayed a police checkpoint with bullets in Olongapo City in Subic also in the north, killing two policemen and a security guard and seriously wounding two other policemen.

    An investigation of the attacks has been launched and the NPA is suspected to be responsible for the incident, the police said.

    Police chief Director General Edgardo Aglipay said the NPA were known to step up their attacks just ahead of their anniversaries on Dec. 26.

    He also noted that the rebels announced in October that they would step up their attacks.

    The currently 8,800-strong NPA, which has been waging insurgencies in remote areas in the Philippines since 1969, has been listed as terrorists by the US and European Union governments. Enditem