China accused the US of becoming "the biggest driver of militarsation" in the contested South China Sea, as tensions between Washington and Beijing look set to swamp a regional Asian summit.

US-China rivalry is expected to dominate discussion at this year's ASEAN conference, which comes just days after Beijing launched ballistic missiles in the flashpoint waters as part of live-fire exercises.

Beijing claims the majority of the resource-rich South China Sea, invoking its so-called nine-dash line to justify its alleged historic rights to the key trade waterway, also contested Vietnam, the Philippines, Malaysia, Brunei and Taiwan.

As tensions simmer, Chinese Foreign Minister Wang Yi told an online meeting of foreign ministers from Southeast Asian countries that "the United States is becoming the biggest driver of militarisation of the South China Sea."

Wang said that China's greatest interest in the waters was "peace and stability", while accusing the US of "creating tension and seeking profit from it".

South China Sea
Beijing claims the majority of the resource-rich South China Sea. Photo: AFP / Ted ALJIBE

"The United States is becoming the most dangerous factor damaging peace in the South China Sea," Wang added, according to state news agency Xinhua on Thursday.

China has reinforced its claim to the South China Sea by building up small shoals and reefs into military bases with airstrips and port facilities.

It rejected a 2016 UN-backed tribunal's ruling that its claims were without legal basis.

This year's ASEAN summit is the first meeting since the US announced sanctions on two dozen Chinese companies over Beijing's construction of artificial islands in the disputed waters, which Beijing blasted as "tyrannical".

US Secretary of State Mike Pompeo, meanwhile, accused the Chinese Communist Party this week of being engaged in a "clear and intensifying pattern of bullying its neighbours."

A fresh spat between China and the Philippines over Scarborough Shoal -- one of the region's richest fishing grounds -- also hangs over the talks.

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