US Vice President Kamala Harris held talks with Southeast Asian leaders on the South China Sea
US Vice President Kamala Harris held talks with Southeast Asian leaders on the South China Sea AFP

US 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 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.

"To keep differences under control, what is essential now is to oppose picking sides, to oppose bloc confrontation and to oppose a new Cold War," Li told regional leaders on Tuesday.

Harris held her own talks with Southeast Asian leaders on "the importance of upholding international law in the South China Sea", according to a statement from her office.

Thursday's summit will be the first time top US and Russian officials have sat around the same table in almost two months, after American and European officials condemned Moscow's top diplomat at a July ministerial meeting over its ongoing Ukraine invasion.

Joining them will be Indian Prime Minister Narendra Modi, Japanese PM Fumio Kishida, South Korean President Yoon Suk Yeol, Canada's Justin Trudeau and Australian PM Anthony Albanese, as well as leaders from the Association of Southeast Asian Nations (ASEAN) bloc.

The talks come several months after US Secretary of State Antony Blinken travelled to Beijing, the first visit by the most senior US diplomat in nearly five years, where he met Xi as well as former foreign minister Qin Gang.

While the gathering can bring major players together, its ability to help resolve a range of regional and global disputes is limited, experts say.

"It's a sign of the Asean convening power but lately we can say that the East Asia summit is broken. It has been turned into a forum for talking points," said Aaron Connelly, senior fellow at Singapore-based think tank IISS.

While Thursday's meeting will be more geopolitical in scope, big powers used earlier talks in Jakarta to shore up alliances and lobby the Southeast Asian bloc.

Li travelled on a Chinese-funded high-speed train project between capital Jakarta and the Javan city of Bandung with a senior Indonesian minister on Wednesday.

Harris held separate meetings with Indonesian President Joko Widodo and Philippine President Ferdinand Marcos Jr -- both ASEAN members -- on the sidelines of the summit.

"The Vice President reaffirmed the United States' ironclad alliance commitment to the Philippines, and highlighted the role the US-Philippines alliance plays in ensuring a free, open and prosperous Indo-Pacific," her office said in a statement.

South Korea's Yoon reportedly pushed for the bloc to counter North Korea's nuclear threats, calling for any military cooperation with the country to stop.

United Nations Secretary-General Antonio Guterres will also address the summit later on Thursday.