Cambodia, which currently holds the bloc's rotating chairmanship, said there had been too little progress on a "five-point consensus" agreed by leaders last year to try to defuse the crisis gripping Myanmar.

The country has been in turmoil since the military ousted Aung San Suu Kyi's civilian government a year ago, with more than 1,500 civilians since killed in crackdowns on anti-junta protests, according to a local monitoring group.

"Since there has been little progress in carrying out ASEAN's Five-Point Consensus, the ASEAN member states did not reach a consensus to invite Myanmar SAC's foreign minister [Wunna Maung Lwin] to participate in the upcoming foreign ministers' retreat," Cambodia foreign ministry spokesman Chum Sounry told AFP.

Myanmar's military government calls itself the State Administration Council, or SAC.

"We have asked Myanmar to send a non-political representative instead," Chum Sounry said.

The snub comes after the 10-nation Association of Southeast Asian Nations (ASEAN) took the unprecedented step of barring junta leader Min Aung Hlaing from a summit in October.

It represented a rare rebuke from ASEAN, long seen as a toothless talking shop, but which has sought to lead diplomatic efforts to tackle the Myanmar crisis.

Myanmar is increasingly isolated on the international stage, with Cambodian strongman ruler Hun Sen's January visit the first by any foreign leader since the generals seized power.

But violence has continued, with anti-junta groups clashing regularly with the military, and the World Bank has warned Myanmar's economy likely contracted by almost a fifth last year.

In a statement on Wednesday, ASEAN called for an immediate end to violence and for its special envoy to be allowed to visit the country soon.