MANILA/HANOI: Indonesia's top diplomat began a Southeast Asian tour on Wednesday to try to patch up an internal rift within the ASEAN group over territorial disputes in the South China Sea, saying the split represented a critical moment for the regional bloc.

The 10-nation group could not agree a concluding joint statement at a ministerial meeting last week, riven with discord over how to address China's increasingly assertive role in the strategic waters of the South China Sea. It was the first time in almost half a century it has failed to deliver a communique.

The Association of Southeast Asian Nations' reputation for harmony and polite debate was left in tatters by the Phnom Penh meeting. One ASEAN diplomat accused China of buying the loyalty of Cambodia and some other states with economic largesse.

Indonesia, the region's biggest country and one seen as a neutral given it has no claim to the disputed waters, has taken on the role of mediator -- tasked with drawing up a code of conduct to prevent any acts of brinkmanship spilling over into conflict.

"Unfortunately last week there were some difficulties but I believe ... what too k place in Phnom Penh was an exception, it's not the rule," In donesia's Foreign Minister Marty Natalegawa sai d in Hanoi, the second stop on his regional tour after Manila.

"Let's keep it that way, let's keep it as an exception , " he said, adding the divide represented a "critical moment" for the group's unity.

Natalegawa said he received the backing of both the Philippines and Vietnam on Wednesday to push ahead with a South China Sea code of conduct, and also expressed ho pes of pro ducin g a statement of unity at the end of his trip this week.

"The end product is having a common ASEAN position on the South China Sea," Natalegawa told reporters in Manila.

"That's why I am now in ASEAN capitals identifying core issues of the South China Sea. I believe we can find other means to ensure there is no vacuum in ASEAN."

The South China Sea has become Asia's biggest potential military flashpoint. Beijing's sovereignty claim over the huge area has set it against Vietnam and the Philippines as the three countries race to tap possibly huge oil reserves.

CAMBODIAN CHALLENGE

Natalegawa said he was leaving Vietnam on Wednesday evening for Bangkok and will conclude his trip with a meeting in Phnom Penh to try to convince his Cambodian counterpart to "restore ASEAN cohesion and unity on the South China Sea".

Cambodia was at the centre of the storm over the failed communique, accused of siding with China which had objected to the mention of a standoff with the Philippines in the contested waters. Beijing maintains the dispute should be resolved bilaterally.

The discord exposed how deeply ASEAN's member states have been polarised by China's rapidly expanding economic influence in the region.

Natalegawa said there was a need to push for a binding code of conduct and a declaration allowing for safe passage of ships in the disputed waters.

"The next task (is) to pursue in an aggressive way ... the code of conduct on the South China sea," he said adding there was a need "to see the code of conduct adopted now, not in three years."

"Then we have a benchmark on which to measure the behaviour of countries in the region," Natalegawa said.

ASEAN brings together Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam. In 2002, the regional bloc and China adopted an informal code of conduct in the South China Sea to avoid conflict and ease tensions. AGENCIES