Chinese President Xi Jinping told his US counterpart Joe Biden Monday that the world was big enough for their two countries to prosper and compete, while warning Washington against crossing Beijing's "red line" on Taiwan.

"Under the current circumstances, China and the United States share more, not less, common interests," Xi told Biden during three hours of talks in Bali, Indonesia, Beijing's foreign ministry said in a statement.

Beijing does not seek to challenge the US or "change the existing international order", Xi reportedly added, calling for the two sides to "respect each other". 

But Xi warned Biden not to cross Beijing's "red line" over the self-ruled island of Taiwan, which the Chinese government claims as its territory.

"The Taiwan question is at the very core of China’s core interests, the bedrock of the political foundation of China-U.S. relations, and the first red line that must not be crossed in China-U.S. relations," Xi told Biden, according to the foreign ministry, adding "resolving the Taiwan question is a matter for the Chinese".

The two leaders were also reported to have discussed the situation in Ukraine, with Xi telling Biden Beijing was "deeply concerned" about the conflict.

"China has all along stood on the side of peace and will continue to encourage peace talks," the Chinese leader was reported to have said. 

"We support and look forward to a resumption of peace talks between Russia and Ukraine."

Xi and Biden both sought to lower the temperature as they met for more than two hours, with the presidents both saying they wanted to prevent high tensions from spilling over into conflict.

In a sign of headway on working together, the White House announced that Secretary of State Antony Blinken will visit China -- the most senior US visitor since 2018.

Biden and Xi, who is on only his second overseas trip since the pandemic, shook hands and smiled before the two countries' flags at a hotel in Bali, where the Group of 20 opens a summit on Tuesday.

Biden, sitting across from Xi at facing tables, said that Beijing and Washington "share responsibility" to show the world that they can "manage our differences, prevent competition from becoming conflict".

Xi, China's most powerful leader in decades who is fresh from securing a norm-breaking third term, told Biden that the world has "come to a crossroads".

"The world expects that China and the United States will properly handle the relationship," Xi told him.

Xi later told him that China and the United States "share more, not less" in common interests, according to a Chinese statement. 

On Tuesday, Xi will hold the first formal sitdown with an Australian leader since 2017, Prime Minister Anthony Albanese announced, following a concerted pressure campaign by Beijing against the close US ally. 

- Absent Putin -

Though he is engaging Xi, Biden has refused since the invasion of Ukraine to deal directly with Russian President Vladimir Putin, who is conspicuously absent from the Bali summit.

The Kremlin cited scheduling issues and has instead sent longtime foreign minister, Sergei Lavrov, who arrived Sunday evening and underwent two health checks at a Bali hospital, according to an Indonesian health ministry official.

Lavrov, 72, denied reports that he was receiving treatment at a Bali hospital, telling Tass news agency that he was in his hotel preparing for the summit.

Lavrov's presence has thrown into question a customary G20 group photo and joint statement, with Russia sure to reject any explicit calls to end its invasion of Ukraine.