U.S. Vice President Kamala Harris, China's premier and Russia's foreign minister will gather at an East Asia summit in Indonesia on Thursday, offering a rare chance of direct, top-level diplomacy between their sparring nations.

The 18-nation meeting will bring Washington and Beijing into contact a day after Premier Li Qiang warned that major powers must manage their differences to avoid a "new Cold War," ahead of the G20 summit this week where President Xi Jinping will be absent.

Interactions between the officials from the world's top two economies will be closely watched as they seek to control tensions that risk flaring anew, over issues ranging from Taiwan to ties with Moscow and a competition for influence in the Pacific.