Myanmar's shadow government has welcomed the exclusion of junta leader Gen Min Aung Hlaing from the regional summit set for later this month.
The opposition, formed by opponents of the ruling military government, said it should be the country's legitimate representative.
However, it will accept the invitation of a neutral alternative Myanmar representative, to be decided at the weekend by the Association of Southeast Asian Nations (Asean).
Asean will invite a non-political representative from Myanmar to its summit, set for October 26 to October 28, in a snub to the military leaders behind a February 1 coup against Aung San Suu Kyi's elected government.
The opposition National Unity Government, which has been outlawed by the military, said the non-political figure who attends the summit must not be a representative of the junta in disguise.
“Asean excluding Min Aung Hlaing is an important step but we request that they recognise us as the proper representative,” said its spokesman Dr Sasa.
The decision was an unusually bold step for the consensus-driven bloc, which traditionally favours a policy of engagement and non-interference.
A spokesman for Myanmar's military government blamed “foreign intervention” for the decision that it said was against the objectives of Asean, the Asean Charter and its principles.
Myanmar has been in turmoil since the coup, which ended a decade of tentative democracy and economic reform. Thousands of its opponents have been arrested, including San Suu Kyi.
Security forces have killed more than 1,100 people, according to the Assistance Association for Political Prisoners, an activist group that has tracked the arrests and killings. The military has called its opponents “terrorists".