Surin Pitsuwan said that as more heavyweights were becoming dialogue partners of Asean, with the United States and Russia joining this year's EAS in Bali for the first time, Asean risked "being directed from behind by outsiders".

"Asean will have to be extremely careful not to overload our own forum to the point where Asean will be unable to maintain its centrality and leadership as convenor of the forum," Surin said.

"Our stage is getting crowded and the heavyweights are coming on our stage. We should maintain the balance among these giants of contending interests," he said. Surin urged Asean "not to bite more than we can chew".

"We have attracted so much attention, but we need a mechanism or working process that gives us a sense of control, of balance, and of ownership," he said.

He added that Asean's major dialogue partners had an agenda to defend their sometimes conflicting interests through Asean forums.

This year's EAS is scheduled to take place on Saturday, two days after the 19th Asean Summit tomorrow. The 18 EAS includes the 10 Asean countries and regional powers Australia, China, India, Japan, New Zealand and South Korea. The US and Russia are new members.

Surin was speaking to a small group of journalists from Asean countries at a hotel in Nusa Dua, a resort in southern Bali.

Regarding territorial conflicts in the South China Sea involving mainland China, Taiwan and four Asean countries, Surin said "careful handling" was needed to avoid "any unintended consequence".

He said the countries involved in claiming the Spratly Islands and other maritime territories in the South China Sea were aware that they have to show the world they can settle this dispute through talks. He said deals could be done between Asean and China and among the Asean countries involved.

Regarding Burma's bid for Asean chairmanship in 2014, Surin said "things are moving in the right direction, with some fundamental changes taking place" in Burma to fulfil conditions for its chairmanship.

The Asean leaders are to decide at this week's summit about Burma's chairmanship.