SINGAPORE (AFP) - Political prisoners in Myanmar and a Thai-Cambodia border crisis dominated talks between Southeast Asian foreign ministers Monday, pushing a bold new EU-style charter to the sidelines.

The Association of Southeast Asian Nations (ASEAN) ministers sat down to the business end of their annual meeting after expressing hope that Myanmar opposition leader Aung San Suu Kyi could soon be released from house arrest.

Asked whether the democracy icon would be freed within months under a technical deadline set in Myanmar law, Indonesian Foreign Minister Hassan Wirajuda said: "That's our hope."

They have also received assurances that Thailand and Cambodia would show "utmost restraint" to avoid armed conflict over a dangerous border dispute, Singapore Prime Minister Lee Hsien Loong said in his opening remarks.

The meetings will culminate in a gathering on Thursday of the 27-nation ASEAN Regional Forum, Asia's top security and political grouping which includes the United States, China and the European Union.

The talks began with a dinner Sunday when the ministers expressed their "deep disappointment" over the extension by one year of Aung San Suu Kyi's house arrest and called on Myanmar's junta to release all political prisoners.

The strong language stood in contrast to ASEAN's usual practice of skirting controversy in the name of non-interference, and came before Myanmar on Monday formally ratified the new ASEAN charter.

Singapore's Foreign Minister George Yeo raised the prospect of the Nobel laureate's release, saying his Myanmar counterpart had reiterated that the junta is legally permitted to hold a citizen for up to six years.

Aung San Suu Kyi has spent most of the past 18 years under house arrest, with the most recent spell beginning in May 2003.

Asked whether the Myanmar's minister's comments meant she could be freed in the coming months, Yeo said: "I am just repeating to you what he told me and I think that is not an inaccurate inference."

Myanmar's treatment of its democratic opposition is a perennial embarrassment for the bloc, comprised of Brunei, Cambodia, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand and Vietnam.

The group is often dismissed as a "talking shop" which has lacked the spine to confront Myanmar's military leadership over its flagrant human rights abuses.

But Singapore's Lee said early ratification of the new charter -- which commits members to standards of human rights and democracy and envisages the creation of a huge free-trade zone of more than 500 million people by 2015 -- was essential if the group was to throw off its do-nothing image.

"The timely ratification and implementation of the charter will itself be a signal of ASEAN's resolve," he said.

"ASEAN cannot take its continued relevance for granted. If our efforts to achieve faster and deeper integration falter, ASEAN may well be sidelined."

Myanmar on Monday became the seventh member state to ratify the charter.

Thailand, Indonesia and the Philippines have yet to do so, with Manila saying previously that it will hold back until Myanmar releases political prisoners and improves its behaviour.

Lee also said ASEAN's intervention to calm tensions on the Thai-Cambodia border -- where hundreds of troops are facing off around an 11 century Hindu temple on a disputed piece of land -- and its leadership of the international aid effort in cyclone-hit Myanmar were also evidence of its new resolve.

"The crisis tested ASEAN's unity... Fortunately ASEAN responded," he said of the response to Cyclone Nargis which hit southern Myanmar on May 2.

A joint ASEAN-UN-Myanmar disaster assessment report on the cyclone, which left 138,000 dead or missing, is due to be presented at the meeting later Monday.

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