The Association of Southeast Asian Nations (ASEAN) on Thursday opened a summit on the Indonesian island of Bali, expected to tackle issues including maritime disputes and reform in Myanmar.
Opening the meeting, the host nation's President Susilo Bambang Yudhoyono said that the 10-nation ASEAN "wishes to play a greater role in the affairs of the world, to reach out to the world".
In an apparent reference to the South China Sea, where China is embroiled in disputes with several members of the bloc, he said: "We must ensure the stability and security of our region.
"ASEAN must continue to play a proactive role to facilitate and engage itself in the resolution of issues."
The leaders are set to discuss Myanmar's bid to host the grouping in 2014, which ASEAN's foreign ministers backed this week, saying it was a reward for reform gestures from the new military-backed government.
"We must continue to engage all leaders in the region," Yudhoyono said.
On Saturday the meeting will widen into the East Asia Summit, which also takes in Australia, China, India, Japan, South Korea and New Zealand, and this year welcomes new members the United States and Russia.
In recent days Beijing and Washington have traded warnings over the handling of the South China Sea territorial wrangle, setting the stage for a confrontation in Bali.