Chinese and Russian leaders Xi Jinping and Vladimir Putin will attend the G20 summit on the resort island of Bali this November, a longtime adviser to the Indonesian president said on Friday.

Andi Widjajanto, former cabinet secretary and unofficial adviser to President Joko Widodo, who is popularly known as Jokowi, told Reuters the two leaders would join the summit.

"Jokowi told me that Xi and Putin are both planning to attend in Bali," Widjajanto, who heads the National Resilience Institute, told Reuters.

On Thursday, Jokowi told Bloomberg News that both leaders had given him their assurances. Indonesian presidential officials did not respond to requests for confirmation of the report.

The Chinese foreign ministry did not immediately respond to a Reuters request for comment. A Kremlin spokesperson declined to comment to Bloomberg, but another official familiar with the situation told the news agency Putin plans to attend the meeting in person.

The trip would be significant given it would be Xi's first time outside China since January 2020, when he visited Myanmar.

China maintains a zero-COVID policy that has all but shut its borders to international travel.

Since then, Xi made his only trip outside of mainland China on June 30, visiting Hong Kong to mark the 25th anniversary of the handover of the territory from British control.

Xi is widely expected to secure a precedent-breaking third leadership term during a once-in-five-years congress of the ruling Communist Party scheduled for this autumn, most likely before he would head to Bali for the mid-November G20 gathering.

No dates have been announced for the party congress, but the last two took place in late October and early November.

Chinese officials are also reportedly making plans for a November meeting in Southeast Asia between Xi and U.S. President Joe Biden, who is expected to attend the G20 summit in Bali, according to a report in the Wall Street Journal.

As head of the G20 this year, Indonesia has faced pressure from Western countries to withdraw its invitation to Putin over his country's invasion on Ukraine, which his government calls a "special military operation".

Indonesia has also invited Ukrainian leader Volodymyr Zelenskiy to attend the Bali summit.

Jokowi has sought to position himself as mediator between the warring countries, and has in recent months travelled to meet both the Ukrainian and Russian presidents to call for an end to the war, and seek ways to ease the global food crisis.

This week, Jokowi said both countries have accepted Indonesia as a "bridge of peace".