Disputes over sovereignty in the South China Sea could become violent but China and Southeast Asia are showing a sense of urgency in trying to ease tensions, the ASEAN chief said Tuesday.

Regional divisions about how to handle China on the issue prevented the Association of Southeast Asian Nations (ASEAN) from issuing a joint statement after a July summit in Phnom Penh for the first time in its 45-year history.

But ASEAN Secretary General Surin Pitsuwan said "good signs" were emerging from informal talks this week in the Thai resort of Pattaya between the 10-nation bloc and China.

"Now both sides are saying we want to get (a code of conduct) done as soon as possible because it doesn't serve anybody's interests (to delay). It's a yo-yo but at least now they agree to talk," he told reporters after a speech in Kuala Lumpur.

"Both sides display a sense of urgency that we can't let the world live in this sense of anxiety and not knowing which direction we are going to go -- it could spill out into the open, it could become violent."

However, he did not offer detailed comment on what he expects from an ASEAN summit set for November 15-20, again hosted by its current chair Cambodia.

He said "a flurry of exchanges among senior people in the region" took place after the July summit in Phnom Penh, leading to a six-point agreement a week later.

"There has been rather intense communication going on so we can put the issue, at least, under containment," he said.

ASEAN announced the six principles and vowed to work towards a "code of conduct" in the disputed sea where tensions have flared, with Vietnam and the Philippines accusing Beijing of increasingly aggressive behaviour.

Diplomats had said a key point in the July impasse was a refusal by Cambodia, a close China ally, to mention bilateral maritime disputes in a joint statement.

That pitted the current ASEAN chair against Manila, which wanted a reference to a months-long standoff with Beijing over a disputed shoal.

"It's a traumatic experience for ASEAN not being able to issue a joint communique for the first time in our history," Surin said.

China claims sovereignty over nearly all of the resource-rich sea, which is home to vital shipping lanes. But ASEAN members the Philippines, Vietnam, Malaysia and Brunei have overlapping claims in the area.