The Philippines president Rodrigo Duterte claims that as a young gang member he killed an opponent in a knife fight for looking at him.

The controversial strongman was speaking about his time as a gang member to the local Filipino community in the Vietnamese city of Da Nang on Thursday (9 October).

He said: "Jail? Jeez. When I was a teenager, I was in and out of jail.

"One fight there, another here -- at the age of 16, I killed someone. A person, really. During a fight. Stabbing. That was when I was 16 years old, just because we just looked at each other."

The 72-year-old leader added: "How much more now that I am president? "You f**k with my countrymen, I won't let you off the hook. Never mind about the human rights advocates."

The Philippines leader was speaking on the eve of the Asia-Pacific Economic Cooperation summit in Vietnam, where he is due to hold talks with US President Donald Trump who is touring the region.

Duterte was elected in last year's presidential elections after promising a crackdown on the Southeast Asian country's drug scourge, during which time police and vigilantes groups have been accused murdering thousands of suspected dealers.

The President's hardline approach remains popular at home, but abroad critics say he is behind a widespread policy of extrajudicial murder.

Duterte denies inciting police or others to kill, but last year said would be "happy to slaughter" three million drug addicts and called then US president Barack Obama a "son of a whore" for criticising his war on drugs.

This is not the first time Duterte has admitting to murder. Last year he said killed suspected criminals during his time as mayor of Davao City, on the southern Philippine island of Mindanao.

He said: "In Davao, I used to do it personally. Just to show the guys that, if I can do it, why can't you?

"And [I'd] go around Davao with a motorcycle, with a big bike around, and I would just patrol the streets, and looking for trouble also. I was really looking for an encounter so I could kill."

Duterte State of the Nation address
Philippine President Rodrigo Duterte gestures as he delivers a speech to the nation's Congress Noel Celis/AFP