US President Joe Biden and his Chinese counterpart Xi Jinping agreed in talks Monday that nuclear weapons should never be used, including in Ukraine, the White House said.

"President Biden and President Xi reiterated their agreement that a nuclear war should never be fought and can never be won and underscored their opposition to the use or threat of use of nuclear weapons in Ukraine," it said in a statement.

The pair held their first face-to-face talks since Biden took office on the sidelines of a G20 meeting expected to be dominated by the war in Ukraine.

The pair shook hands at the start of the meeting, with Biden saying the superpowers shared the responsibility to show the world that they can "manage our differences, prevent competition from becoming conflict".

The White House said he had told Xi that Washington would "continue to compete vigorously" with China, but "this competition should not veer into conflict".

Biden raised objections to China's "coercive and increasingly aggressive actions toward Taiwan," the White House said after three hours of talks aimed at avoiding conflict between the rival superpowers.

And he told Xi the world should encourage North Korea to act "responsibly", after a record-breaking series of missile launches by Pyongyang and growing fears of a new nuclear test.

Biden says 'confident' China 'not looking' for North Korea to escalate
Nusa Dua, Indonesia (AFP) Nov 14, 2022 –

China does not want to see North Korea "engage in further escalation" after a spate of recent missile tests, US President Joe Biden said after talks with his Chinese counterpart.

"I'm confident China's not looking for North Korea to engage in further escalation," Biden said after talks with Xi Jinping in Bali, Indonesia.

He warned more provocation from Pyongyang risked Washington building up its own regional capacities — something Beijing bitterly opposes.

The US leader said he told Xi that Beijing had an obligation to make it clear to Pyongyang that it should not conduct a nuclear test.

"I made it clear as well that if they did (conduct a test)… we would have to take certain actions that would be more defensive on our behalf," Biden said.

"We will do what it needs to defend our capacity, to defend ourselves and our allies, South Korea, as well as Japan," he said.

The US leader was pushing China to use its influence to rein in North Korea after the wave of missile tests raised fears the reclusive regime will soon carry out its seventh nuclear test.

China, Pyongyang's main diplomatic and economic ally, joined Russia in May in vetoing a US-led bid at the UN Security Council to tighten sanctions on North Korea.

Washington has responded to North Korea's sanction-busting missile tests by extending exercises with South Korea and deploying a strategic bomber.

Biden said the US would build up further regional capacities if North Korean tests continued.

"They would not be directed against China but it would be to send a clear message to North Korea," he said.

Earlier this year, Biden said he would not exclude a meeting with North Korean leader Kim Jong-un if he were "sincere" but said any such talks with the unpredictable dictator would be unlikely.