Previously it had refused to send “non-political representatives” to attend but two senior bureaucrats are representing Myanmar at the talks in Vientiane.
The military’s readiness to re-engage diplomatically was a sign of its “weakened position”, a Southeast Asian diplomat told AFP on condition of anonymity.
Myanmar’s generals have yet to make any meaningful counterattack following an offensive by ethnic armed groups in October that seized swaths of territory along the border with China.
The losses triggered rare public criticism of its top leadership.
Foreign ministers were struggling to agree on a common position on Myanmar for the meeting’s communique, a diplomatic source told AFP.
“Myanmar is not resolved yet but we’re almost there,” the source said, requesting anonymity to talk to the media.
A draft ASEAN communique seen by AFP said ministers “strongly condemned” the continued violence.
The crisis has divided the bloc, with Indonesia, Malaysia and the Philippines calling for tougher action against the junta.
Thailand has held its own bilateral talks with the generals as well as detained democracy leader Aung San Suu Kyi.
