"No more American influence. No more American exercises. It's time to say goodbye, my friend. Your stay in my country was for your own benefit," Mr Duterte said, referring to his country's long alliance with the US, its former colonial power.

"I will not go to America anymore. I will just be insulted there," he added, before once again referring to US President Barack Obama as the "son of a whore".

The comments aimed at the US's strongest ally in Asia over decades will further alarm policy-makers in the US and its allies in Asia and the Pacific, including Australia.

Mr Duterte's dramatic shift from the foreign policy of his predecessor Benigno Aquino threatens to sabotage Mr Obama's much-vaunted policy to "pivot" US military resources and diplomatic influence to Asia, analysts say.

The US has an agreement to rotate thousands of its forces and military weaponry and equipment through Philippines military bases at a time of heightened tensions over China's aggressive claim to almost the entire South China Sea.

During a four-day visit to China, the abrasive Mr Duterte said he was fed up with his country's foreign policy being dictated by a Western agenda.

"What kept us from China was not our own making. I will chart a new course," he said.

Mr Duterte heaped praise on China and set aside his country's dispute with Beijing over territorial claims in the strategic waters of the South China Sea.

Accompanied by 400 businesspeople, the 71-year-old president discussed Chinese investments in his country's infrastructure, obtaining cheap loans, the opening of Chinese markets to Philippine fruits and help in his deadly crackdown on drugs that has been criticised by the US, United Nations and human rights groups.

Mr Duterte described a recent international court ruling on the South China Sea which favoured the Philippines as only a "piece of paper with four corners", handing China a public relations bonanza after its humiliating defeat on the claim.

"The arbitral award gives us the right. China has the historical right. And they're insisting. In this situation, do we argue, or do we just talk? I would say, let us put it off to some other day."

The overtures to China, which many Filipinos regard as a bully, have drawn criticism in the Philippines where Mr Duterte's drugs crackdown, which has left thousands of people dead, is hugely popular.

Jay Batongbacal, an expert on maritime affairs and the law of the sea at the University of the Philippines, said

Mr Duterte is "taking a huge risk, betting all on China's goodwill and beneficence without the insurance provided by the diversified, multilateral support of historical and traditional friends and allies".

"Over the long term, China unmistakably stands to gain much, while the Philippines' fate remains uncertain," he added.

Richard Heydarian, a Manila-based policy adviser and author of Asia's New Battlefield: The USA, China and the Struggle for the Western Pacific, said even Mr Duterte's strongest supporters are worried about the direction of his foreign policy "particularly in terms of military co-operation with America".

China's nationalistic Global Times newspaper said Washington has treated Manila as a "pawn", adding that Mr Duterte was now "re-designing Philippine foreign policy based on Philippine interests".

In Manila on Wednesday, supporters of Mr Duterte's anti-US stand clashed violently with police outside the US embassy.

A police van rammed protesters, injuring about 10. Police fired tear gas and arrested at least 23 people among the crowd of about 1000.