The fight began last week after Kyaw Moe Tun, who was appointed as ambassador to the UN by the now-ousted democratically-elected government, defied his country's new military dictators.

He gave an emotional 10-minute speech to the UN General Assembly on Friday in which, voice trembling, he urged the world to oppose last month's "illegal and unconstitutional" coup.

At the end, Kyaw Moe Tun raised the three-finger salute used by pro-democracy movements across Southeast Asia.

Other participants in the meeting to discuss the crisis in Myanmar applauded him.

The US ambassador called his speech "courageous and brave".

But Myanmar's regime-appointed Ministry of Foreign Affairs called it "high treason" and dismissed Kyaw Moe Tun.

He was replaced by his deputy.

Yet Kyaw Moe Tun says he remains the ambassador, leading to confusion over who is Myanmar's legitimate representative to the world body in New York.

UN spokesman Stephane Dujarric on Tuesday left open which of the two diplomats will be officially recognised as the ambassador, describing it as a "unique situation" that needs to be sorted out legally.

Dujarric reported that two letters had reached UN Secretary General Antonio Guterres.

In the first, Kyaw Moe Tun stressed that he remains in the post as the coup leader took power illegally.

In another letter, Myanmar's Foreign Ministry said that Kyaw Moe Tun had been fired and that his deputy Tin Maung Naing was in charge.

According to the United Nations, both diplomats are still entitled to enter the headquarters on New York's East River.

But as to which of them will be recognised to speak at meetings of the General Assembly, Dujarric said that would be up to other member states.

Australian Associated Press