Chinese foreign minister Wang Yi will attend a G20 gathering this week, China announced Tuesday, setting up a possible first encounter with new US Secretary of State Rex Tillerson.

Last week, as Sino-US tensions over Taiwan simmered, it seemed Wang would skip the meeting of top diplomats from the Group of 20 nations opening in Bonn Thursday to be at a Beijing event.

But following a conciliatory call between US President Donald Trump and his Chinese counterpart Xi Jinping, Wang has suddenly found time to go to the high-level gathering, Chinese foreign ministry spokesman Geng Shuang told reporters at a regular press briefing.

He declined to comment on whether Wang would meet Tillerson, who is expected to make his international diplomatic debut at the Bonn conference.

The summit will mark the highest-level brush yet between China and the Trump administration, which angered Beijing by questioning a decades-old position acknowledging that Taiwan is not separate from China.

But Trump on Friday reaffirmed US adherence to the so-called "One China" policy in a phone call with Xi.

Trump described the conversation as "very warm", in an apparent effort to ease frictions.

The billionaire politician has threatened to upend decades of multilateralism and raised fears of trade wars with his "America first" positions.

Geng, the Chinese foreign ministry spokesman, said Beijing hopes the G20 gathering will "send positive signals on supporting multilateralism, enhancing global governance and creating an innovative, interconnected, open and inclusive world economy".

Trump's insurgent campaign for the White House included frequently lashing out at China, which he accused of currency manipulation and stealing American jobs.

He raised eyebrows in the wake of his election victory with a protocol-busting telephone conversation with Taiwan's President Tsai Ing-wen.

He later threw doubt on the "One China" policy, suggesting that it was up for negotiation and could form part of talks on trade, drawing rebukes from official Chinese media.

Taiwan has been ruled separately since the two sides split in 1949 at the end of a civil war.