Southeast Asian nations were at loggerheads Thursday over how hard to press China on its contentious efforts to assert control over the flashpoint South China Sea, with the issue threatening to fray regional unity.

China has sparked alarm by expanding tiny reefs and constructing military posts, steps viewed by some of its neighbours as violating a regional pledge against provocative actions in the area.

Diplomatic sources told AFP that the Philippines and Vietnam in particular were pushing for stronger language on Chinese land reclamation, which could help shore up Beijing's disputed territorial claims.

But there was pushback from traditional China allies among the 10-member Association of Southeast Asian Nations (ASEAN), which is meeting this week in Malaysia, they added.

"China's friends are taking a hard stance," said one diplomat familiar with the drafting.

The diplomat did not specify which countries were taking a hard line, but Cambodia, Laos and Myanmar traditionally ally with China within ASEAN.

The tug-of-war raises the spectre of a 2012 ASEAN meeting hosted by Cambodia, when the bloc was unable for the first time in its four-decade history to issue a joint statement.

Cambodia was accused of precipitating the debacle by refusing to allow criticism of China over its maritime territorial assertions.

"China has already figured out how ASEAN works on the South China Sea, it knows how to divide us. Look at what happened in Cambodia," one diplomat at the talks in Kuala Lumpur told AFP.

- 'There are difficulties' -

Envoys from 27 nations -- including the United States and China -- were in Kuala Lumpur for the final day of regional security talks dominated by long-running disputes over the strategic sea.

Beijing claims control over nearly the entire South China Sea, a key shipping route thought to hold rich oil and gas reserves.

Vietnam, the Philippines, Malaysia and Brunei -- all ASEAN members -- also have various claims, as does Taiwan, many of which overlap.

Each year the regional bloc, which prides itself on its history of consensus diplomacy, releases a joint communique after the annual meeting of its foreign ministers, which took place Tuesday.

Singapore Foreign Minister K. Shanmugam told reporters Thursday morning that the joint statement was supposed to have been completed the previous day.

"It has not been finalised as of now. There are difficulties," he said.

"The paragraphs relating to the South China Sea are causing some problems," he added.

A draft of the communique obtained by AFP makes no mention of halting reclamation.

Instead it warns that recent developments in the sea "have the very potential of undermining peace, security and stability".

It adds: "There is an imperative need to urgently address the erosion of trust and corrosion of confidence amongst parties on these matters".

Delegates said they still hoped to get a final joint statement by the end of the day.

The United States and Southeast Asian nations have called for a halt to further land-reclamation and construction.

China had so far refused, but on Wednesday Chinese Foreign Minister Wang Yi said land reclamation had "already stopped".

However some delegates in Kuala Lumpur have played down those claims.

One diplomat told reporters: "They're not saying they're stopping construction, nor are they saying they'll stop future reclamation."

The Philippines said it would only be satisfied once Beijing halts construction in the disputed sea.

"Beyond halt to reclamation, the Philippines' position includes (a) halt to construction and halt to all actions that escalate tension," presidential spokesman Herminio Coloma told reporters.