Southeast Asian nations Tuesday backed away from establishing a united front against China over territorial disputes in the South China Sea, as Beijing warned against the initiative.

The Philippines is pushing for a joint stand on the issue among Association of Southeast Asian Nations (ASEAN) leaders meeting on Indonesia's Bali island this week, according to an internal document obtained by AFP.

China has caused disquiet in Washington and Asian capitals with its claim to all of the South China Sea, a region that encompasses vital shipping lanes and which is believed to sit atop vast oil and mineral reserves.

China's rival Taiwan, as well as ASEAN countries the Philippines, Vietnam, Malaysia and Brunei, also lay claim to all or part of the area, and Manila pushed for a meeting of all six countries involved.

But Beijing, which prefers to negotiate individually with its weaker neighbours, said it was not appropriate to discuss territorial rows at the East Asia Summit, which will take place in Bali this week.

"China believes that the disputes should be resolved through peaceful consultations between parties directly concerned," China's assistant foreign minister Liu Zhenmin told journalists at a briefing in Beijing.

"The intervention of outside forces is not helpful for the settlement of the issue, on the contrary it will only complicate the issue and sabotage peace and stability and development in the region," he said in an apparent reference to the United States, which is joining the East Asia Summit this year.

Beijing's economic and political clout mean that ASEAN members cannot afford to cause offence, making the establishment of a unified position difficult.

Despite deep concern in the region over the maritime dispute, there were few backers for the initiative proposed by the Philippines, which has taken a forthright stand on the issue in recent years.

"China is showing a positive step by organising seminars and workshops, that is very positive. ASEAN should reciprocate on that," Malaysian Foreign Minister Anifah Aman told AFP.

"To introduce another forum will complicate the matter further," he said, adding it was more constructive to concentrate on a non-binding declaration of conduct, even though critics have dismissed it as toothless.

Cambodia's Foreign Minister Hor Namhong also declined to support Manila's proposal.

"We are not against," he told AFP, laughing, before adding: "The problem is how to avoid... duplication."

ASEAN secretary general Surin Pitsuwan indicated the concept was being put on the diplomatic back burner, saying it "remains to be discussed further".

He echoed other ministers' views that the region should focus on a legally binding code of conduct, which has eluded agreement for years.

"That issue is gaining momentum and we are making progress. There will be some efforts here and there in order to strengthen this momentum," he said.