PHNOM PENH, Nov 11, 2022 (BSS/AFP) - Southeast Asian leaders agreed Friday to engage Myanmar opposition groups as they seek ways to quell the country's escalating bloodshed which has seen thousands killed in clashes since last year's coup.

The Myanmar crisis dominated the first day of a gathering of the Association of Southeast Asian Nations (ASEAN) regional bloc in Phnom Penh that US President Joe Biden will join on Saturday.

Myanmar has spiralled into bloody conflict since the military ousted Aung San Suu Kyi's civilian government in February last year.

ASEAN agreed a "five-point consensus" peace plan with Myanmar in April last year but the junta has so far ignored it and the bloc has struggled for months to come up with ways to enforce it.

Frustrated by the generals' foot-dragging, leaders on Friday tasked their foreign ministers with drawing up "an implementation plan that outlines concrete, practical and measurable indicators with specific timeline".

In a 15-point statement thrashed out over two days of difficult talks among foreign ministers, the bloc agreed to "engage all stakeholders soon".

"Engagement would be done in a flexible and informal manner, primarily undertaken by the Special Envoy of the ASEAN Chair on Myanmar," the leaders' statement said.

This will likely involve meeting representatives of Myanmar's National Unity Government (NUG), a self-declared parallel body dominated by former lawmakers from Suu Kyi's party.

The NUG considers itself to be the country's legitimate government but the junta regards its members as "terrorists", and engaging with the group would be a significant step for ASEAN.

- 'This is a warning' -

The leaders also warned the generals that if they do not step up, the bloc could expand a ban on junta figures attending ASEAN meetings.

"This is a warning, this is a strong message from the leaders," Indonesian Foreign Minister Retno Marsudi told reporters.

Within the bloc, Indonesia has been one of the main voices calling for tougher action on the junta, along with Malaysia and Singapore.

Philippine Assistant Secretary for ASEAN Affairs Dan Espiritu said that after more than a year of junta inaction it was time to "implement some other alternative plan in view of the limited progress".

He characterised the situation in Myanmar as "critical and fragile with growing violence".

The five-point plan calls for an end to violence, dialogue between all sides in Myanmar mediated by the ASEAN envoy and humanitarian aid.

Last year's coup slammed the door on Myanmar's brief dalliance with democracy after decades under army rule.

Earlier this month Singapore's Foreign Minister Vivian Balakrishnan warned that the Myanmar military had "a very high tolerance for pain, very high tolerance for isolation" and the crisis could take decades to resolve.

Elsewhere on Friday, the summit agreed "in principle" to let East Timor join ASEAN, granting it observer status while it works towards full membership.

- US pressure -

ASEAN has blocked Myanmar junta chief Min Aung Hlaing from attending the gathering in Phnom Penh, which Chinese Premier Li Keqiang is also attending.

China, the bloc's biggest trading partner, has historically had good ties with the Myanmar junta, though it has voiced some unease at the ongoing chaos in the country.

Western powers have heaped sanctions on the junta and the United States has urged ASEAN to take a "forceful" stance to squeeze the junta to reduce the violence, which escalated in recent weeks with deadly military air strikes on civilian targets including a school and concert.

Daniel Kritenbrink, the top US diplomat for East Asia, said Myanmar would be a top subject when Biden meets ASEAN leaders on Saturday.

On Sunday Biden will sit down with Li in Phnom Penh at the East Asia Summit, which takes in ASEAN members plus other regional powers including Russia, Australia and New Zealand.

A day later the US leader flies to a high-stakes meeting with his Chinese counterpart Xi Jinping on the sidelines of the G20 summit in Indonesia.

Myanmar state media have slammed ASEAN's involvement, accusing the bloc of being a "lapdog for the US", while the junta warned against imposing a timeline on the peace process, saying it could lead to "negative implications".