Chinese state-media accused the Philippines of using the ASEAN group of nations as an "accomplice" in the violation of its sovereignty claims in the South China Sea on Saturday, and warned of a potential "counterstrike".

The editorial in the overseas edition of the People's Daily, the mouthpiece of China's ruling Communist Party, came as the Association of Southeast Asian Nations (ASEAN) was due to meet in Brunei, with disputes in the Sea expected to dominate discussions.

The Philippines, which has sought closer ties with Washington amid territorial disputes with Beijing, "calls on the United States as 'patron'" and uses ASEAN as an "accomplice," the editorial said.

It added that the Phillipines was guilty of "seven sins," including the "illegal occupation" of parts of the Spratly Islands, strengthening control over disputed coral reefs, inviting foreign companies to develop oil and gas resources in disputed waters, and promoting the "internationalisation" of the Sea.

"If the Philippines continues to provoke China... a counterstrike will be hard to avoid," the editorial said.

Members of the ASEAN group hope to reach a legally binding code of conduct aimed at easing tensions over disputed areas in the Sea, which is claimed almost in its entirety by Beijing, leading to long-running disputes with several neighbouring countries including the Philippines.

China has resisted ASEAN efforts to create a legally binding code to govern conduct on the sea, and analysts say Beijing will continue to oppose any agreement weakening its claims.

The Philippines this year sought UN arbitration over its dispute with China, a move condemned by Beijing.

A US destroyer joined the Philippine Navy's flagship this week for military exercises close to the Scarborough Shoal, which China insists it owns.

Countries around the region have boosted spending on their navies in recent years in response to tensions, raising fears of a military conflict.