Philippines President Rodrigo Duterte ordered the killings of around 1,000 criminals and political opponents while he was a city mayor - and shot one of them himself, a former assassin has claimed.

Edgar Matobato, 57, told the country's Senate that he personally carried out about 50 abductions and deadly assaults.

"We'd remove their clothes, burn the bodies and chop them up," he said.

One of the victims - a suspected kidnapper - was apparently fed alive to a crocodile in 2007 in southern Davao del Sur province.

Others were buried at a quarry owned by another member of the Davao Death Squad (DDS), which was made up of policemen and ex-communist rebels.


Image: Rodrigo Duterte was mayor of Davao City before becoming president

Speaking under oath, Mr Matobato said: "Our job was to kill drug pushers, rapists, snatchers."

But he added that the targets were not always criminals.

One was apparently the boyfriend of Mr Duterte's sister, another was a local broadcaster who had criticised the then Davao City mayor, and four were a local rival's bodyguards, he claimed.

Mr Matobato alleged that an additional pair were enemies of Mr Duterte's son Paolo, who is now vice mayor of Davao City.

"They were killed like chickens," he said.

He also claimed that one of the killings was carried out by Mr Duterte himself.

A confrontation at a roadblock with a justice department official in 1993 generated into a shootout.

August: Philippines Police Kill Hundreds In Their War On Drugs

"Mayor Duterte was the one who finished him off," Mr Matobato said.

"Jamisola (the justice department official) was still alive when he (Duterte) arrived. He emptied two Uzi magazines on him."

Mr Matobato said he withdrew from the squad after feeling guilty and entered a government-run witness protection programme.

But when Mr Duterte became president in June he left the programme, fearing for his life.

He said he had decided to give evidence because "I wanted the people to know so the killings will stop."

Since Mr Duterte became president, a crackdown on suspected drug users and dealers has left more than 3,000 people dead.

The Senate committee inquiry is being led by a critic of the policy, Senator Leila de Lima.

There has also been international concern. US President Barack Obama has been among those urging Mr Duterte's government to stop the killings and pay more attention to human rights and the rule of law.

But Mr Duterte has accused Ms de Lima of being involved in illegal drugs - something she has denied.

He has also angrily rejected criticism from overseas, recently backtracking after describing the US president as the "son of a whore".

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Mr Duterte's spokesman, Martin Andanar, dismissed Mr Matobato's allegations: "The Commission on Human Rights already investigated this a long time ago and no charges were filed," he said.

Paolo Duterte described Mr Matobato's testimony as "mere hearsay".

"I will not dignify with an answer the accusations of a madman," he said.

One senator, former national police chief Panfilo Lacson, warned Mr Matobato that his admissions that he was involved in killings could see him jailed.

"You can be jailed with your revelations," Mr Lacson said.

"You have no immunity."