The Association of Southeast Asian Nations is paralysed by differences over how to deal with regional superpower China's claims to strategic islands in the South China Sea, analysts said.

Lack of consensus between members of the 10-nation block over how to proceed in the negotiations with China over a proposed Code of Conduct in the sea was the biggest sore point at a two-day summit in Cambodia this week.

Philippine Foreign Secretary Albert del Rosario said there was a "big disagreement" on Tuesday over the issue, while Cambodian Prime Minister Hun Sen angrily played down media reports of a rift.

In the end, the leaders issued a statement Wednesday showing a veneer of unity and promising to "intensify efforts" toward the full implementation of an agreement, signed 10 years earlier, to "promote peace".

The language was strikingly similar to that used at the end of an ASEAN summit in Indonesia last year, demonstrating the bloc's failure to resolve its differences on an issue of considerable international concern, analysts said.

"This is a weak statement but it's understandable in the sense that ASEAN has been unable to find a common position regarding the South China Sea," said former Thai diplomat Pavin Chachavalpongpun, an expert at the Institute for Southeast Asian Studies in Singapore.

China and several ASEAN countries have rival claims to uninhabited islands in the sea, which is believed to be rich in hydrocarbons and straddles strategic shipping lanes vital to global trade.

The United States claims a "national interest" in keeping the waterway open for business, and has recently stepped up military ties with the Philippines, one of the claimants, as part of its foreign policy "pivot" to Asia.

US commanders have called on China to be more transparent about its intentions in the sea, where there have been clashes between Chinese, Philippine and Vietnamese vessels in recent years.

Bridget Welsh, an associate professor in political science at Singapore Management University, said the "noncommittal nature" of the ASEAN response "serves to emphasise the persistence of differences".

"This shows that the issue is still serious and the members recognise it as such, but they clearly have not reached a consensus on how to move ahead with China," she said.

US Seventh Fleet commander Vice Admiral Scott Swift said in November that while ASEAN had made "significant progress" to ease tensions, he remained concerned about "any tactical trigger with strategic implications".

China's claim to the Spratly archipelago -- based on the so-called Nine Lines dotted on an 18th-century map -- competes with those of Vietnam, the Philippines, Taiwan, Brunei and Malaysia.

China and Vietnam also have a long-standing dispute over the Paracel island group. A Vietnamese diplomat said late last year the region was "rife with smouldering tensions that threaten to escalate into full-scale conflicts".

Analysts said a visit by Chinese President Hu Jintao to Cambodia on the eve of the regional talks was a thinly disguised attempt to pressure Phnom Penh, which holds the ASEAN chair in 2012, to keep the sea off the agenda.

Cambodia's main concern when it comes to relations with China is boosting trade and investment. Hu pledged last week to double bilateral trade between the two countries to $5 billion by 2017, according to Hun Sen.

ASEAN secretary-general Surin Pitsuwan, who is keen to overcome the bloc's image as a talking shop, said the recent rise in tensions had given a "sense or urgency" to talks over the Code of Conduct.

"It has given the global community a sense of concern that this could lead to open conflict which will not be in the interest of any party," he told AFP.

"So we have the support of the international community to resolve this problem peacefully, effectively as soon as possible, and we are working on it."

But he admitted there were "shades of difference" between ASEAN members -- drawn between those with claims in the sea and those with no claims -- over when to include China in negotiations over the Code of Conduct.