Philippine President Rodrigo Duterte said Wednesday he wants US troops out of his country in the next two years and is willing to scrap defence pacts with longtime ally Washington if necessary.

The remarks during a high-profile visit to Japan follow a series of anti-American tirades by the firebrand leader.

‘I want, maybe in the next two years, my country free of the presence of foreign military troops,’ Duterte told an economic forum in Tokyo, in a clear reference to US forces, ahead of a summit with Japanese Prime Minister Shinzo Abe.

‘I want them out and if I have to revise or abrogate agreements, executive agreements, I will,’ he added.

The US has a small number of Special Forces on the southern island of Mindanao to aid counter-terrorism operations.

But Duterte has already said he wants US troops out of Mindanao because their presence stokes tensions on the island where Islamic militants have waged a decades-long separatist insurgency.

Duterte has repeatedly attacked the US while cosying up to Beijing, upending his nation's foreign policy in comments that have sometimes been quickly retracted.

Philippine Foreign Secretary Perfecto Yasay, asked to clarify the president's remarks, said that Duterte did not mean US troops would be ousted, stressing that ‘our national interests still continue to converge’.

The acid-tongued leader arrived in Tokyo on Tuesday on his first visit to Japan since taking office on June 30, looking to persuade executives his country is ‘open for business’, after seeming to overturn Manila's traditional diplomatic alliances.

The 71-year-old has slammed Washington for questioning his violent crime crackdown, which has claimed some 3,700 lives and attracted widespread international criticism.

- South China Sea -

Duterte has also insulted US President Barack Obama, calling him a ‘son of a whore’ and announcing a ‘separation’ from the US during a visit to Beijing last week.

Although he quickly walked back from his comments, saying that ‘separation’ did not mean he would ‘sever’ ties, he reiterated his calls on Wednesday for an end to all joint war games with the US.

‘This will be the last manoeuvre war games between the United States and the Philippines' military,’ he said of an event hosted in recent weeks by the Philippines.

In Tokyo, Duterte and Abe later stressed during a joint media appearance their countries' common values as democracies that respect the rule of law.

‘The Philippines will continue to work closely with Japan on issues of common concern in the region... including the South China Sea,’ Duterte said after their summit.

Japan announced loans totalling 21.3 billion yen ($204 million) to help improve the Philippines' maritime safety as well promote peace and agriculture on Mindanao.

Although his Japanese hosts depend on the US for security, Tokyo has so far not responded to Duterte's diatribes, while Washington has taken a calm approach.

Abe had worked to improve bilateral relations with Duterte's predecessor, Benigno Aquino, providing patrol boats to support Manila in its territorial row with Beijing over rival claims to the South China Sea.

The Philippines took Beijing to an international tribunal over its extensive claims in the region and won a resounding victory in July.

But Duterte has not pressed the issue with Beijing, instead working to improve ties and attract billions of dollars in Chinese loans and investments.

Duterte, in his speech at the economic forum, attempted to calm worries in Japan over his trip to China, assuring his audience that he was not seeking military ties with Beijing, just a closer economic relationship.

‘We did not talk about arms, we did not talk about stationing of troops,’ he said. ‘We avoided talking about alliances, military or otherwise.’