Malacanang maintained on Friday it would no longer make a comment on any statement of Jose Maria Sison, founding chairman of the Communist Party of the Philippines.

"As I said, he's not worthy of comment," Presidential Spokesperson Harry Roque said in a text message to reporters.

He refused to react on Sison's interview with the Foreign Correspondents Association of the Philippines` (FOCAP) Thursday where he accused President Rodrigo Duterte and son former Davao City Vice Mayor Paolo Duterte as the "biggest protector of drug trade" in the Philippines.

He said Duterte was a kumpadre of Peter Lim, an alleged drug lord.

Presidential son, Paulo, in a separate statement, called Sison as a "pathological liar," branding his allegation as a repetition of an "old gossip" propagated and sowed around by an anti-Duterte senator, who was also a "rabid anti-communist."

He was apparently referring to opposition Senator Antonio Trillanes IV.

"Joma Sison’s accusation that my father and I are the biggest protectors of illegal drugs in the country confirms that the founder of the oldest terror group in Southeast Asia is completely losing it," he said.

"Mr. Sison, who a pathological liar himself, was parroting a liar. This echolalia showed how much Mr Sison was willing to take for the sake of public attention, propaganda, and significance," Paolo said.

"It also showed the nature of his politics and principles ? where it’s acceptable for enemies to sleep together in one bed, speak one language, and unify forces and work together until the common target is toppled down," the younger Duterte added.

He predicted that Sison's "insanity," like the bloody leftist revolution in the country, would fail.

"And Mr Sison and his organizations ? the CPP-NDFP-NPA (National Democratic Front of the Philippines-New People's Army) ? will be remembered in history for their contribution in the revolution that victimized the oppressed, the poor, and ultimately, the growth and development of the Philippines. Mr. Sison, the father of the oldest terror group in Southeast Asia, is a disgrace to this country," he stressed. Celerina Monte/DMS