By Hader Glang

ZAMBOANGA CITY, the Philippines 

Philippine police revealed Saturday that communist insurgents are believed to be responsible for the latest fatal attack on troops despite peace overtures made by incoming President Rodrigo Duterte.

The Philippine Inquirer cited a report sent to the national police force as saying that two soldiers were killed Saturday afternoon by suspected New People’s Army (NPA) members in northern Luzon island.

Quoting the report from police in Pilar town in Sorsogon province, Police Sr. Insp. Maria Luisa Calubaquib said an investigation is ongoing to determine if the fatalities occurred during an ambush or an encounter believed to be staged by the group.

The incident came a day after three troops were killed in two separate attacks by suspected NPA rebels in troubled southern Mindanao island.

A soldier was killed and another wounded when an army headquarters in Agusan del Norte province was attacked, while two other soldiers were left dead after an ambush in Davao Oriental province Friday morning.

The incidents followed the arrests Thursday of four suspects believed to be high-ranking NPA members in Agusan del Norte.

After winning the May 9 election, Duterte made overtures toward the Communist Party of the Philippines -- of which the NPA is the armed wing -- and its political front, the National Democratic Front (NDF).

Preliminary talks between the NDF and the incoming Philippines administration have been scheduled in Oslo, Norway for next week, and incoming peace process adviser Jesus Dureza left the archipelago for Europe on Friday.

"We look forward to a fruitful meeting under the auspices of the Norwegian government in the sidelines of the 'Oslo Forum'," local media quoted Dureza saying in a statement.

Since March 1969, the NPA has been waging one of Asia’s longest running insurgencies in the country, which -- according to the military -- has claimed more than 3,000 lives over the past eight years.

The military estimates that the number of NPA members has dropped from a peak of 26,000 in the 1980s to less than 4,000.

Duterte is set to assume office June 30.