Ex-Philippine leader Fidel Ramos has resigned as special envoy to China after criticising President Rodrigo Duterte's tirades against the United States and deadly war on crime.

Philippine President Rodrigo Duterte said Thursday that Japanese Prime Minister Shinzo Abe asked him to explain his anti-American rhetoric during summit talks.

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.

Philippine President Rodrigo Duterte was set Wednesday to persuade Japanese executives his country is "open for business", after upending traditional alliances by insulting the US and making overtures to China.

President Rodrigo Duterte on Tuesday urged foreign businesses in the Philippines worried about his deadly drug war to "pack up and leave", as he launched another anti-American tirade before flying to Japan to attract investments.

Philippine President Rodrigo Duterte's fiery rhetoric and deadly crime war are becoming a growing concern around the world, the top US envoy for Asia warned on Monday in Manila.

President Rodrigo Duterte's shock "separation" from the United States has thrown Philippine foreign policy into confusion, with the Americans saying they are baffled and some of his top aides contradicting him.

Philippines' President Rodrigo Duterte declared his "separation" from longstanding ally the United States in Beijing on Thursday, as he rebalances his country's diplomacy towards China.

Philippines' President Rodrigo Duterte and his Chinese counterpart Xi Jinping pledged to enhance trust and deepen cooperation Thursday, Chinese officials said, as Manila's new leader seeks to rebalance his country's diplomacy away from the US.

China offered fresh praise for visiting Philippine President Rodrigo Duterte on Wednesday, lauding "friendly" relations as the combative leader reconfigures his country's diplomatic alliances.

Philippine President Rodrigo Duterte is willing to hold military exercises with China but not longtime ally the United States, Chinese media quoted him Monday as saying on the eve of a state visit.

Philippine President Rodrigo Duterte vowed Sunday he will not "barter" away territory and economic rights ahead of a visit to Beijing, where he hopes to mend ties frayed by a row over the South China Sea.