Controversial Filipino President Rodrigo Duterte has labelled US counterpart Barack Obama a “son of a bitch” and warned him not to question his policy of extrajudicial killings.

Since gaining power in June, Mr Duterte has engaged in a vicious war on drugs, which has seen around 2,400 people killed with impunity by hit squads, drawing international criticism.

But before heading to Laos for the ASEAN Summit on Monday, Mr Duterte said he was a leader of a sovereign country and answerable only to the Filipino people.

He said Mr Obama should be respectful and refrain from throwing questions at him about the killings, "[or] son of a bitch, I will swear at you in that forum."

Mr Duterte was answering a reporter's question about how he intends to explain recent events in the Philippines to Mr Obama.

He continued: "Who is he to confront me? As a matter of fact, America has one too many to answer for.

"Everybody has a terrible record of extrajudicial killings."

The most controversial quotes from Rodrigo Duterte Show all 9 1 /9 The most controversial quotes from Rodrigo Duterte The most controversial quotes from Rodrigo Duterte On killing drug addicts “These sons of whores are destroying our children. I warn you, don’t go into that, even if you’re a policeman, because I will really kill you. If you know of any addicts, go ahead and kill them yourself as getting their parents to do it would be too painful” The most controversial quotes from Rodrigo Duterte Message to China “I will go there on my own with a Jet Ski, bringing along with me a [Phillipino] flag and a pole, and once I disembark, I will plant the flag on the runway and tell the Chinese authorities, ‘Kill me’ ” AP The most controversial quotes from Rodrigo Duterte Christmas message to law-breakers “If you do not want to stop, and just continue committing crimes, then this would be your last Merry Christmas” AP The most controversial quotes from Rodrigo Duterte On sex life “I was separated from my wife. I’m not impotent. What am I supposed to do? Let this hang forever? When I take Viagra, it stands up” AFP/Getty Images The most controversial quotes from Rodrigo Duterte On the drugs trade “None of my children are into illegal drugs. But my order is, even if it is a member of my family, ‘kill him'" AP The most controversial quotes from Rodrigo Duterte Insulting the Pope “We were affected by the traffic. It took us five hours. I asked why, they said it was closed. I asked who is coming. They answered, the pope. I wanted to call him: ‘Pope, son of a wh**e, go home. Do not visit us again’” AFP/Getty Images The most controversial quotes from Rodrigo Duterte Joke about rape “I saw her face and I thought, 'What a pity... they raped her, they all lined up. I was mad she was raped but she was so beautiful. I thought, the mayor should have been first” AFP/Getty The most controversial quotes from Rodrigo Duterte Insulting Barack Obama "Mr Obama should be respectful and refrain from throwing questions at me about the killings, or son of a bitch, I will swear at you in that forum" REUTERS The most controversial quotes from Rodrigo Duterte On Abu Sayyaf Islamic militants "If I have to face them, you know I can eat humans. I will really open up your body. Just give me vinegar and salt, and I will eat you. If you annoy me to the fullest... I will eat you alive. Raw" EPA

The strongman president made his name as a tough law enforcer and has advocated the killing of drug users and suppliers, offering his protection to police officers who do his bidding.

Around 900 of the dead were killed in police operations, while the remainder are “deaths under investigation” – a term human rights campaigners say is a euphemism for vigilante murders.

At the same conference, Mr Duterte told journalists: "Plenty [of drug dealers] will be killed until the last pusher is out of the streets. Until the [last] drug manufacturer is killed we will continue.”

Mr Obama is not the only world leader to have felt the sharp end of Mr Duterte’s tongue, with Mr Duterte having used the same insult towards the United Nations following criticism of his policies.

“Maybe we’ll just have to decide to separate from the United Nations,” Mr Duterte said in late August. “If you are that disrespectful, son of a bitch, then I will just leave you.”