MANILA: Philippines boxing icon Emmanuel "Manny" Pacquiao says he took all kinds of drugs as a teenager but fully supports President Rodrigo Duterte, whose vicious anti-drugs campaign has led to the killing of more than 3,000 people, mostly users and pushers, in three months.

Pacquiao, now a senator and a close ally of the president, also said Duterte was anointed by God to discipline the Filipino people and his authority must be respected.

"The president, he doesn't know my experience with drugs," said Pacquiao (37), adding he was confident it wouldn't damage their close relationship.

"He always gives a chance to people who want to be changed," said the boxer-turned-lawmaker in an interview in his senate office.

"I tried drugs...many kinds of drugs, all kinds of drugs," he said, dressed in the traditional white Filipino barong shirt and trousers.

Pacquiao said this phase lasted for years "before I became a champion".

Duterte, who took office on June 30, has made the war on drugs the central part of his presidency, saying narcotics are destroying the nation of 100 million people. A total of 3,171 people have been killed since then, including users and pushers, nearly two thirds by unknown assailants and the rest in legitimate police operations, according to police.

The friendship between the boxer known as "The Destroyer" and the president known as "The Punisher" dates back at least 15 years as Pacquiao tells it, to a boxing ring in Davao, where Duterte helped organise one of his fights.

"He helped me a lot. He helped me with the promotion when I started in boxing. One of my fights held in Davao, he sponsored it," said Pacquiao, a southpaw who has been an eight-division world champion. "He helped with the promotion, financially as well."

Pacquiao has the initials of a group called Guardians Mindanao Brotherhood tattooed on his wrist, as does Duterte, according to media reports. "It's a fraternity," Pacquiao said.

Guardians Brotherhood started as a soldiers group that was later disbanded.

Pacquiao was born in the town of Kibawe in the Mindanao region of the southern Philippines, about 80 km (50 miles) from Davao city, where Duterte was mayor and congressman since 1988.

STOWAWAY MADE GOOD

Pacquiao's family was dirt-poor, and, according to his autobiography, the family lived in a thatched hut. His father harvested coconuts and his mother sold peanuts.

Pacquiao did odd jobs to survive and stowed away on a boat to Manila as a teenager, where he started competitive boxing.

According to Forbes, he has earned $500 million from purses, pay-per-view and endorsements so far in his career.

Pacquiao could not recall his first meeting with Duterte but said it was when he was 22 or 23. Since then, Pacquiao said they had frequently met for meals and that he is a godfather to Duterte's grandson.

Even now, Pacquiao says, Duterte often calls after a fight to congratulate him.

Pacquiao calls the president by his nickname, Digong, a play on his first name, Rodrigo.

"He's a very nice person, a nice guy," Pacquiao said, adding that the president was totally unlike the popular perception that he was foul-mouthed and aggressive. "He is a respectful person, a hospitable person, a friendly person."

Pacquiao said blaming the killings on the president was unfair because it was drug lords and drug pushers who were killing one other.

"God put him there for a reason, for purpose - to discipline the people," he said, adding that the people had to respect the authority and "the anointed one".

Pacquiao supported Jejomar Binay, a rival of Duterte, in the presidential campaign, but switched allegiance to Duterte later. Now he is one of the president's closest allies, and one of his first acts in the senate was to file a bill to reinstate the death penalty for drug-related and serious crimes, one of Duterte's key plans.

Last week, Pacquiao helped sideline one of Duterte's most outspoken critics, fellow Senator Leila De Lima, by leading a motion to oust her as the chair of a high-profile committee examining the president's links to vigilante death squads in Davao during his time as mayor.

"It's not my intention to remove her from the chairmanship of the committee to stop the investigation," Pacquiao said. "The investigation will continue. We just want to implement it in the right way."

For Pacquiao, Duterte is doing nothing wrong.

"In the past administrations, people didn't respect the law, the leader, the authorities," he said. "What Duterte is trying to do is let the people know - and put it in their hearts and minds - that you need to respect the law of the land."

Pacquiao then left for a training session. Often described as the best pound-for-pound boxer in the world, he has come out of retirement to challenge World Boxing Organisation welterweight champion Jessie Vargas in November.