MANILA - Communist Party of the Philippines founding chairman Jose Maria Sison on Tuesday said there was no existing ceasefire in place when communist rebels attacked a convoy of the Presidential Security Group in North Cotabato last week.

Speaking to ANC, Sison said the two PSG vehicles had no markings indicating they were government property when they reached a checkpoint manned by the rebels in Arakan town.

"There is no ceasefire, no prior identification, no prior permission for the other side to be in the spot. Whether there is a ceasefire or not, there has to be some kind of clearance," the Netherlands-based Sison said in the interview via Skype.

"It has been done before. [President] Duterte is not lacking in connection... Duterte could have contacted the responsible organ there through people he knows."

Sison also raised doubts on why the vehicles were in the area.

"Why did those 2 vans appear in that spot? Why should they be in the area as if seeking some encounter?" he asked.

Authorities earlier said the convoy was carrying 10 PSG officers, 7 of whom were reportedly trapped for an hour inside their armored vehicle as the rebels opened fire.

• LOOK: PSG vehicle attacked by Reds riddled with bullet holes

The remaining 3 officers were on board the other, non-bulletproof vehicle, fled to the nearby Barangay Lorega in Kitao-kitao, Bukidnon. They reached safety even after one of the tires of vehicle burst due to the assault.

The gunmen eventually withdrew and shot dead a militiaman they encountered along the way. Four PSG members meanwhile were wounded in the encounter.

The attack was among a string of hostilities that later prompted President Rodrigo Duterte to cancel peace talks with communist rebels.

• Duterte: Reds are 'enemies of the state'

DUTERTE SLAMS AMBUSH

Duterte on Tuesday revealed that he was on board the ambushed convoy.

"Ginagawa ko ang magagawa ko. E pu******* pati ang convoy ko inambush, pati ako gustong patayin. Sino kausapin ninyo? Alam niyo bang andoon ako, tapos sabihin Duterte mag-usap tayo," he said in a speech before activists after delivering his State of the Nation Address.

Sison, however, questioned the President's claim. "He made up a story, it seems, he was at the checkpoint area, Arakan."

The CPP leader also said that Duterte should have notified the communists of his plan to pass by the area.

"I don't know whether he really was there. He must have been stupid not to give advance notice. Even without the ceasefire, because of the long relations with him, he could have contacted the people he knows in the movement that he would have been prowling or whatever he would be doing in the area," Sison said.

"He himself does not know how to take care of himself if that is the case."

FICKLE PEACE TALKS?

Sison also criticized Duterte for flipflopping on his promise to end the decades-long communist insurgency in the country.

"Duterte keeps on flipflopping. Sometimes he would say that he doesn't like to negotiate anymore, but sometimes he puts in a qualification that 'If you don't like it anymore, we will not want to do it anymore,'" he said.

He noted that Duterte, his former student, seemed to "reopen the doors" to peace negotiations when he directly addressed militants after the SONA.

• Duterte confronts militants at SONA rally

But within hours, the President threatened to bomb Lumad schools for allegedly spreading subversive ideas, Sison said.

The peace process with the communists, an initiative important to Duterte, has been fraught with breakdowns, with both sides blaming each other for attacks launched during talks.

Presidential Spokesperson Ernesto Abella however earlier clarified that the government has not formally terminated the talks despite Duterte's pronouncements. -- With Reuters