Andrew Kirkwood described the situation as "very concerning."

"The people of Myanmar are really living in a severe crisis at the moment," he said in a virtual meeting with reporters.

"The United Nations was supporting a million people affected by the conflict here inside the country," he said.

But that number "now is three million, that's a tripling in over the last eight months" since the February 1 coup.

"It's is a very concerning situation, definitely the worst situation I think in the country that I've seen," said Kirkwood, who has been in Myanmar for a decade.

"There is no way we can reach those three million people with the resources that we have at the moment," he continued, calling for more funding.

In a recent report UN Secretary-General Antonio Guterres called for an "urgent" international response to the political crisis created by the coup in Myanmar.

The military has carried out a bloody crackdown on opponents, with more than 1,100 civilians killed and 8,400 imprisoned, according to the Assistance Association for Political Prisoners (AAPP).