The 10-member ASEAN will meet Li at their gathering in Vientiane after a day of talks among themselves dominated by the Myanmar civil war.

Japan's new Prime Minister Shigeru Ishiba and President Yoon Suk Yeol of South Korea will also join the summit, along with Indian PM Narendra Modi.

The ASEAN leaders on Wednesday repeated their longstanding calls for restraint and respect for international law, according to a draft summit chairman's statement seen by AFP.

Beijing claims almost the entirety of the South China Sea, a waterway of immense strategic importance through which trillions of dollars in trade transits every year.

But several ASEAN members, the Philippines, Vietnam, Indonesia and Brunei, also have competing claims to various small islands and reefs. 

The meeting with Li comes after a slew of violent clashes at sea, particularly with the Philippines around the Spratly Islands.

Chinese coast guard and other vessels have rammed, water-cannoned and blocked Philippine government vessels.

And earlier this month Vietnam issued an angry condemnation after some of its fishermen were attacked and robbed off the Paracel Islands by what it called "Chinese law enforcement forces".

Beijing responded that the islands are its sovereign territory and its personnel were taking action to stop "illegal fishing" by the Vietnamese.

China has for years sought to expand its presence in contested areas of the South China Sea, brushing aside an international ruling that its claim to most of the waterway has no legal basis.

It has built artificial islands armed with missile systems and runways for fighter jets, and deployed vessels that the Philippines says harass its ships and block its fishers.

The talks with Li are also expected to cover Myanmar, which counts China as its main ally, as the bloc seeks to breathe life into its ailing attempts to end the country's bloody conflict.

ASEAN leaders condemned attacks on civilians and "urged all parties involved to take concrete action to immediately halt indiscriminate violence", according to a draft summit chairman's statement seen by AFP.

ASEAN agreed to a five-point peace plan with the Myanmar junta more than three years ago but generals have ignored it and the bloc has not found a way to compel them to comply.

The conflict that began with the February 2021 coup has left thousands dead and forced millions to flee their homes.

On Friday the leaders will be joined by US Secretary of State Antony Blinken, Russian Foreign Minister Sergei Lavrov and others for the annual East Asia Summit.