SYDNEY, July 20 - United States Vice President Joe Biden on Wednesday assured key ally Australia there would be no retreat from Washington's pivot to the Asia-Pacific region regardless of who wins November's presidential election.

Biden dismissed concerns that Republican presidential nominee Donald Trump would abandon President Barack Obama's strategy for the Asia-Pacific if he were to defeat Democratic nominee Hillary Clinton.

"Don't worry about our election. The better angels in America will prevail," Biden said in a speech in Sydney.

"The United States is all in. We've made good on that promise and continue to make good on that promise. We have shown our commitment to lead the region over and over again."

Tensions between the United States and China have been rising in recent months over the East Vietnam Sea, through which more than $5 trillion in trade passes every year.

Biden's visit to the region follows last week's court ruling in The Hague that China has no historic title over the disputed waters.

Beijing has dismissed the case, brought by the Philippines, as a farce and accused Washington of fuelling tensions.

Neither Trump nor Clinton have been vocal supporters of Obama's Asia-Pacific pivot in their campaigning, leading some to question about Washington's support for the strategy.

Biden insisted that the U.S. military would continue to underpin freedom of navigation in the East Vietnam Sea, regardless of which party controls the White House from 2017.

"The United States has kept and will keep a laser focus on the future in the Asia-Pacific," he said.

"America is the linchpin and we want to ensure the sea lanes are secure, the skies remain open. That is how to maintain the free flow of commerce, that is the life-blood of this region."

China claims most of the East Vietnam Sea, which is rich in energy and fishing resources. Brunei, Malaysia, the Philippines, Taiwan and Vietnam have rival claims.