In a special issue of Dangadang, a copy of which was obtained by The STAR, an article said the bust was destroyed by New Peoples Army (NPA) rebels posing as tourists.
"This explains why residents did not notice the plan," the newsletter said, adding that the guerrillas were from the NPAs Chadli Molintas Command.
Dangadang ("warfare" in the local Ilocano dialect) is published quarterly by the Communist Party of the Philippines branch that operates in the Ilocos and Cordillera regions in the northern Philippines. The NPA is the armed wing of the CPP.
The Dec. 29 blast coincided with President Arroyos Christmas retreat in Baguio City, also in Benguet, and embarrassed police and military intelligence agencies.
Military officials and even the Marcoses, however, doubt the NPAs claim of responsibility and suspect that treasure hunters were the culprits.
Since the 1986 ouster of Ferdinand Marcos, persistent rumors held that the strongman secretly amassed tons of gold during his 20-year presidency and buried it in several sites across the Philippines.
Much of the gold reportedly came from the fabled Yamashita treasure, named after the Japanese army general who commanded the Japanese forces in the Philippines during World War II.
According to rumors, the Yamashita treasure was the loot of Japans brutal march across the region. The treasure was buried in several sites in the Philippines to prevent them from falling to US forces but was found by Marcos decades later.
A chicken farmer living only meters from the bust told The STAR that he saw nothing unusual that day and was surprised by the explosion.
According to Dangadang, the rebels measured the concrete beams and posts inside the bust to know how much explosives were needed. The article included a diagram showing where the explosives were placed.
They also measured the busts distance from the nearest houses, school building and the highway. They noted where the nearest police station was and how many police officers were in the area and where they were posted.
The rebels began planting the explosives at 11 p.m. on Dec. 28 and timed the explosion at 1:45 a.m. to make sure they would be long gone by the time the police or the military arrived to investigate.
Local supporters supplied the guerrillas with explosives, the getaway vehicle and temporary lodging, the newsletter said. The bust had "long been requested by the residents to be destroyed," it added.
The massive bust was built in the 1970s on a hillside overlooking a highway in Tuba town in Benguet province. More tourists unexpectedly have been visiting the site since the busts defacement.
The monuments original plan, designed by Filipino sculptor Anselmo Dayag, was to build busts of Marcos and of three other former Philippine presidents Elpidio Quirino, Ramon Magsaysay and Diosdado Macapagal Mrs. Arroyos father and Marcos predecessor in a kind of Filipino version of Mt. Rushmore.
Last year, the United States branded the CPP and the NPA as terrorist organizations in line with its global war on terrorism.
The CPP protested the terrorist tag, saying it is a legitimate revolutionary movement decriminalized after the 1986 ouster of Marcos.
In November, the Arroyo administration announced it will offer amnesty to the rebels to encourage them to lay down their arms and return to normal life, but the offer was rejected.
Mrs. Arroyo indefinitely suspended formal negotiations with the communists in 2001 when the estimated 9,000-strong NPA assassinated congressmen Rodolfo Aguinaldo of Cagayan and Marcial Punzalan of Quezon.
However, the government maintained "back-channel" contacts with the insurgents.