MANILA - A self-confessed "hitman" on Wednesday (Sept 15) has linked President Rodrigo Duterte to over a thousand murders in a span of two decades while he was mayor of the southern city of Davao.

In a testimony before a Senate committee investigating a spate of extrajudicial killings here, Mr Edgar Matobato, 57, recalled how he and his alleged cohorts, including a couple of policemen and former communist partisans, disemboweled and hacked men to pieces, and either torched their remains or dumped them at sea.

Mr Matobato said he took part in these murders as part of a squad of vigilantes Mr Duterte purportedly formed "to kill criminals, drug pushers, snatchers, rapists".

Mr Duterte himself, or active-duty Davao police officers assigned to his office as mayor, would give the orders to kill, he said.

Mr Matobato narrated an incident in 2007 when a government agent hauled a man suspected of running a kidnap-for-ransom gang one evening. That man was fed alive to a crocodile, he said.

The agent, lawyer Dante Gierran, now heads the National Bureau of Investigation.

Later, though, Mr Matobato said his "team" was ordered to also kill a dance instructor of Mr Duterte's sister, a man that Mr Duterte's son Paolo, now Davao vice-mayor, supposedly had an altercation with at a petrol station, and a fixer, he said.

Mr Matobato said Mr Duterte himself unloaded two magazine clips of an Uzi submachine gun on a government agent who figured in a shootout with his men.

He said he was also told that the younger Duterte had ordered the killing of Mr Richard King, a billionaire hotel owner, in 2014 because of a feud over a woman.

He also accused Mr Paolo Duterte of using drugs and sheltering "Chinese" friends who were his narcotics suppliers. "He'd sometimes run amok when he was high," he said.

Mr Matobato said he was a member of the anti-communist Civilian Armed Forces Geographical Unit when he was drafted in 1988 into a group of assassins that were known in Davao as the "Lambada boys".

He admitted that he himself executed at least 50 people.

He said he had hurled a grenade at a mosque in 1993 after militants bombed the Davao Cathedral. He said he was in the same room when Mr Duterte ordered a certain officer to "massacre Muslims in that mosque".

He said he remembered his unit having killed over 1,000 people - most of them tortured, killed and buried at a quarry owned by a policeman in Davao or an empty lot near a shopping mall, or hacked to pieces and their remains weighed down by sand or rock and thrown at sea "for the fish to feed on".

Mr Matobato said Mr Duterte and his son "had people killed in Davao like these people were chickens".

Reacting to the allegations, Communications Minister Martin Andanar said Mr Matobato was recycling allegations that the Justice Ministry had already dismissed.

"I don't think he's capable of giving a directive like that," he said.

Mr Duterte's spokesman Ernesto Abella said: "I believe, as in all cases, all citizens should maintain a sense of sobriety and maintain a sense of objectivity. After all, people do make statements every day. And while this person may sound credible, it is imperative that each and every one of us properly weigh whatever has been said."

Mr Paolo Duterte, the President's son, said Mr Matobato's testimony was "bare allegations and, in the absence of proof, are mere hearsay. I will not dignify the accusations of a madman".

Senators allied with Mr Duterte poked holes into Mr Matobato's testimony.

Senator Panfilo Lacson, a former police chief, cited mistakes with some of the dates and locations that Mr Matobato mentioned, including the place where the billionaire Mr King was killed.

Mr Lacson that he could not find any information on a certain "Salim Makhdum" that Mr Matobato identified as leader of an "international terrorist network", who was strangled and hacked to pieces allegedly on Mr Duterte's orders.

"If he was a high-value target, we should be hearing about him. I've been Goggling him, and I can't find anything on him," said Mr Lacson.

Senator Alan Peter Cayetano, who ran as Mr Duterte's running mate, suggested Mr Matobato was being used by the Liberal Party of former president Benigno Aquino in a plot to unseat Mr Duterte.

He sought an end to the Senate investigation, and for the chair of the committee probing the killings, Senator Leila de Lima, to step down.

Sen De Lima has been leading investigations into Mr Duterte's anti-war crime that has left in its wake over 3,000 dead since the President took office on June 30.

Mr Duterte, in turn, has accused Sen De Lima of coddling drug kingpins, and called her out for her alleged affair with her driver.