Controversial Philippines president Rodrigo Duterte has reignited his feud with the United States saying they treat his country like 'dogs'.

The volatile new leader was holding a press conference before boarding a flight from Manila to Japan for an official visit, when he launched into another anti-American tirade.

It came a day after the US envoy to Asia branded Duterte's deadly crime crackdown in the Philippines, which has left almost 4,000 suspected drug dealers dead, as bad for business and voiced human rights concerns.

Controversial Philippines president Rodrigo Duterte has reignited his feud with the United States saying they treat his country like 'dogs'

But now the Filipino president has lashed out saying Washington could forget about a military agreement between both countries if he were to be in power longer.

He told reporters: 'They started it, then came out the issue of human rights, the State Department, Obama, EU. They did this to me.

'Then they said, we will cut our assistance. So I said to them, 'son of a whore, do not make us your dogs, as if I am a dog with a leash, and you throw some bread, where I can't reach.'

'The ambassador said something not very nice. You are not supposed to do that because in an election of another country, you should be careful with your mouth.

'I look forward to the time when I no longer see any military troops or soldier in my country except the Filipino soldiers.'

Duterte then flew to Japan, one of the top US allies in Asia, for a three-day visit that is partly aimed at building on two-way trade of more than $18 billion dollars last year.

Upon arrival in Tokyo, Duterte proceeded to a hotel for an event with members of the local Filipino community.

The US envoy to Asia branded Duterte's deadly crime crackdown in the Philippines, which has left almost 4,000 suspected drug dealers dead, as bad for business and voiced human rights concerns

Duterte, a self-proclaimed socialist with close links to communists, announced in Beijing the Philippines' 'separation' from the United States, throwing into doubt a 70-year alliance that is anchored on a mutual defence treaty

More than 100 of them waiting outside gave him an enthusiastic welcome, calling his name and waving small Philippine flags. A smiling Duterte approached them and shook hands.

He will meet with Prime Minister Shinzo Abe and have an audience with Emperor Akihito during the trip, which follows his headline-grabbing state visit to China last week.

Duterte, a self-proclaimed socialist with close links to communists, announced in Beijing the Philippines' 'separation' from the United States, throwing into doubt a 70-year alliance that is anchored on a mutual defence treaty.

He quickly walked back from his comments after returning from China, saying 'separation' did not mean he would 'sever' ties and that the US alliance would continue.

Duterte has previously branded US President Barack Obama a 'son of a whore' and told him to 'go to hell'.

Daniel Russel, the US envoy, said after meeting Philippine Foreign Secretary Perfecto Yasay on Monday that many people around the world were becoming increasingly worried about Duterte's tirades.

'The succession of controversial statements, comments and a real climate of uncertainty about the Philippines' intentions have created consternation in a number of countries,' Russel said.