MANILA (AFP) - Despite foul-mouthed tirades, international outrage and a public spat with US President Barack Obama, Mr Rodrigo Duterte is the most popular politician in the Philippines.

As the politically incorrect president enters the third month of his six-year term, the Asian nation's slums are drenched in blood from a brutal anti-drug campaign that has seen police and shadowy assassins kill nearly 3,000 people.

But 71-year-old Duterte is riding high on record approval ratings, with the acid-tongued and irascible grandfather shrugging off repeated controversies including unprovoked and obscene attacks on the United Nations and the US president, whom he this week called a "son of a whore".

Critics said he was a dictator in the making, but 16 million people voted the former state prosecutor into office earlier this year, a landslide win fuelled by widespread disgust at conventional politicians in a raucous, corruption-ridden democracy.

"He is probably saying things ordinary people would not say because they are fearful or ashamed," political scientist Antonio Contreras told AFP.

"It's hard to explain. It's a machismo thing," said Mr Earl Parreno, from the Manila-based think tank Institute for Political and Electoral Reform, explaining that Duterte represented many people's hope for genuine change.

"Despite his missteps, his insults... what they want really is for him to be given a chance to do something that will have an impact on their lives," he told AFP.

That sense of hope is embodied by Mr Irving dela Cruz, an IT manager who spends at least two hours getting to work through Manila's gridlocked traffic.

"Okay, I don't like his attitude, his swearing, his womanising, all his negative traits. But what he has done and what he continues to do outweighs everything," the 39-year-old told AFP.

"He is transparent, nothing about his personality is faked, and he represents the common man. I feel safer actually," he added.

Mr Parreno said Filipinos generally backed Mr Duterte's bloody anti-crime crackdown not because they were ignorant of their rights but that they were more concerned about their personal safety.

"They really think we need this kind of action," he said. "It is sometimes embarrassing but that is the mind of the masses."

Manila pollster Pulse Asia said 91 per cent of Filipinos supported MrDuterte in their last popularity survey in July, more than a month after he took 38 per cent of the popular vote in the landslide May election. There have been no other surveys since then.

Rights groups, church leaders in the mainly Catholic nation and some lawmakers have joined the US and United Nations in condemning the extra-judicial killings.

"This is a national emergency and the Philippine government particularly President Duterte are instead cheerleading and praising this campaign ... It's absolutely appalling," Mr Phelim Kine, of Human Rights Watch, told Al Jazeera.

"Lawyers, human rights activists understand these things but ordinary people on the streets are not likely to be familiar with that," Dr Contreras said of concerns over democratic rights.

"They (victims) are painted to be criminals, they are demonised as drug addicts," he told AFP.

Mr Duterte's popularity - or notoriety - is extending beyond Philippine borders as he makes his first foreign trip to a summit in Laos this week, according to his spokesman Martin Andanar.

Some foreign ministers as well as delegates at the Association of South-east Asian Nations meeting have been scrambling to take selfies with the Filipino leader, Andanar told reporters Wednesday.

"In spite of the colourful language that he uses, the Asians in the region seem to be able to get - and there seems to be an empathy towards - him," Mr Ernesto Abella, another Duterte spokesman, added.