The Philippines' drug problem is "beyond imagination", boxing legend Manny Pacquiao said on Saturday in Tokyo, defending his hard-liner president's controversial anti-drug campaign.

Pacquiao, a national hero and elected senator, is a high-profile supporter of President Rodrigo Duterte's brutal war on crime that has left more than 3,700 people dead in four months.

"The problem in our country is beyond of our expectation, beyond of our imagination that these illegal drugs in our country is really bad," he said in English at a press conference held by the Foreign Correspondents' Club of Japan. 

"A lot of our government officials, elected officials are involved with this illegal drug," he said, defending Duterte's crackdown which has drawn global condemnation for alleged extrajudicial killings.

Pacquiao, who was elected to the Senate in May, also supports Duterte's call to restore the death penalty for drug traffickers in the mainly Catholic nation. 

He himself is a convert to a conservative Christian sect.

"My main focus is to change our country and hold our president's advocacy because the president and I are very close and join together to clean these illegal drugs in our country," he said.

He was visiting Tokyo to prepare for the opening of a new gym in his chain, the first to appear outside the Philippines.

The 37-year-old boxing superstar shocked the world of sport in September when he admitted in an interview he had used narcotics in his youth.

He said he "sampled" marijuana and "shabu", the local name for the cheap and highly addictive crystal meth stimulant, when he was 15 or 16.

At the Tokyo press conference, he made no secret of the fact he had tried illegal drugs before.

"But when I realised it's not good and I don't like it, then that's why I strongly oppose and fight these illegal drugs," he said.

Source: AFP