Southeast Asian nations are set to discuss Myanmar's governance crisis at a summit in Jakarta on Saturday.
Tuesday's announcement by the 10-member Association of Southeast Asian Nations (ASEAN) comes a day after the European Union imposed stiff sanctions on militarily controlled Myanmar, an ASEAN member state.
The military in Myanmar, which is also known as Burma, overthrew the country's elected leader Aung San Suu Kyi in early February, triggering a popular revolt followed by a violent crackdown on protesters and civilians who want a return to democracy.
At least 738 people have been killed by junta security forces since the crackdown began, according to the Assistance Association for Political Prisoners.
Local media say security forces killed six villagers on Tuesday.
ASEAN's principles of consensus and noninterference restrict it from meddling in the domestic affairs of member nations, but most member states say they plan to send representatives other than heads of states.
Thailand's Deputy Prime Minister and top diplomat Don Pramudwinai will attend the summit instead of Prime Minister Prayuth Chan-ocha. The latter told local reporters that "some other countries will also send their foreign ministers."
It is unclear whether members of Myanmar's military junta will attend the summit, but a Thai government official said junta chief Min Aung Hlaing would be in Jakarta, according to Reuters.
Meanwhile, the European Union handed down sanctions to 10 of Myanmar's military leaders. The sanctions will also affect two giant military conglomerates for "undermining democracy and the rule of law" in Myanmar. The EU also said the sanctions were in response to human rights violations against civilians and protesters who are demanding a return to democratic rule.