Addressing the meeting, Southeast Asian leaders sharply criticised the junta, its lack of cooperation with Asean, and its slow progress towards restoring peace
Myanmar's junta boycotted a Southeast Asian summit Tuesday after its chief was banned from the event, deepening the regime's isolation nine months after it took power in a coup.
The virtual gathering kicked off three days of meetings hosted by the Association of Southeast Asian Nations (Asean), with US President Joe Biden as well as China's premier in attendance.
Myanmar topped the agenda of Tuesday's talks between regional leaders, with the country still in chaos following February's military takeover and the subsequent deadly crackdown on dissent.
Facing calls to defuse the crisis, Asean -- which includes Myanmar -- has drawn up a roadmap aimed at restoring peace but there have been doubts over the junta's commitment to the plan.
Its refusal to let a special envoy meet ousted civilian leader Aung San Suu Kyi prompted the bloc to bar junta chief Min Aung Hlaing from this week's summit.
The putsch snuffed out Myanmar's short-lived experiment with democracy, and Nobel laureate Suu Kyi now faces a raft of charges in a junta court that could see her jailed for decades.
The 76-year-old testified in court for the first time Tuesday in a closed-door hearing, a source with knowledge of the case told AFP, although the content of the testimony was not revealed.
Min Aung Hlaing's exclusion from the Southeast Asian summit was an unprecedented snub from an organisation often seen as toothless.
The junta slammed the decision as a breach of the bloc's policy of non-interference in member states' affairs.
The 10-member group invited a senior official from the junta-appointed foreign ministry in the general's place.
But the regime said on the eve of the meeting that sending a more junior figure would "affect our country's sovereignty and image".
At the opening of the summit, a big screen showed the leaders participating -- with just a blue display carrying the word "Myanmar", where the country's representative was supposed to be.
Addressing the meeting, Southeast Asian leaders sharply criticised the junta, its lack of cooperation with Asean, and its slow progress towards restoring peace.
And Biden, speaking later at a US-Asean summit via video link, denounced the military takeover and "horrific violence" in Myanmar, the White House said.
The president "called on the country's military regime to immediately end the violence, release those unjustly detained, and restore Burma's path to democracy", a statement said, using Myanmar's previous name.
As the summits took place, small pro-junta rallies were staged in several townships in Myanmar's western Rakhine state, where protesters carried portraits of military figures and banners declaring their support for the armed forces, local media reported.
While some have hailed the decision to bar the junta chief as significant, observers think it unlikely the bloc will go further, such as by suspending Myanmar.
And they see little chance of decisions at this week's meetings that could prompt a change of course from the junta.
A statement from the chair of the Asean summit "expressed concern" and called for "the immediate cessation of violence in Myanmar and all parties to exercise utmost restraint".
It made no mention of Myanmar's decision to skip the meeting.
The statement also said concerns were raised about "serious incidents" in the South China Sea -- where Beijing and several Southeast Asian states have overlapping territorial claims.
In his remarks to Asean leaders, Biden also made a veiled reference to countering China, as he seeks to rally allies against Beijing's growing aggression.
He called the bloc "a lynchpin" in a region "where every country can compete and succeed on a level playing field and all nations, no matter how big or powerful, abide by the law".
This year's meetings, hosted by Asean member Brunei, are taking place online due to virus-related travel difficulties.
Biden is also scheduled to take part Wednesday in a summit with Asean and other world leaders, including China's Premier Li Keqiang.