Myanmar's military has been battling on multiple fronts to impose order since its Feb. 1 coup against Aung San Suu Kyi and her elected government sparked nationwide protests. Kayah State, which borders Thailand, is one of several regions where volunteer People's Defense Forces have clashed with Myanmar's well-equipped army, which has responded with artillery and air strikes, triggering an exodus into nearby forests.

"The junta's brutal, indiscriminate attacks are threatening the lives of many thousands of men, women and children in Kayah State," Thomas Andrews, UN special rapporteur on human rights in Myanmar, said in a statement.

"Let me blunt. Mass deaths from starvation, disease, and exposure, on a scale we have not yet seen since the February 1 coup, could occur in Kayah State absent immediate action," he said.

An activist in Kayah State said many displaced people could not be reached including in an area east of Demoso town, about 15 kilometers from the state capital, Loikaw.

"Some people to the east of Demoso have to survive on rice broth as we cannot deliver rice bags to them," said the activist, who asked not to be identified. She said that military authorities had arrested three people trying to deliver aid in the last two weeks.

Power had also been cut in many areas and, along with food, materials for shelter and petrol were also desperately needed, said the activist, who also called for urgent international help.

A spokesman for the junta did not immediately respond to calls requesting comment.

Thailand, which fears a flood of refugees, has expressed its concern about the fighting in Myanmar and urged the junta to take steps agreed with other Southeast Asian countries aimed at setting a course out of the conflict.

The junta has paid little heed to demands from ASEAN to respect a "consensus" agreed in late April to end violence and hold political talks with its opponents.

A rights group says Myanmar security forces have killed at least 857 protesters since the coup, though the army disputes that figure.

Meanwhile, United States President Joe Biden's policy coordinator for the Indo-Pacific region said on Tuesday the situation inside military-ruled Myanmar was deeply concerning and continuing to get worse and the US was looking at all possible scenarios there.

"It's undeniable that the violence is spiraling," Kurt Campbell told an online event hosted by the Center for a New American Security think-thank.

"We're seeing not only challenges from the ethnic insurgencies, but increasingly, much more organized and purposeful and determined opposition on democratic side that has refused to go down."

"It's hard not to be discouraged by what we've seen," he said, when asked if he saw the possibility of state collapse in Myanmar. "I would say the situation inside the country is concerning. And the situation is continuing to get worse. I think we are looking at all scenarios."

Myanmar has been in turmoil since a Feb. 1 military coup, with daily protests in towns and cities and fighting in borderlands between the military and ethnic minority militias, some of which have only existed for a few weeks.

Campbell noted that Myanmar's coup leader Min Aung Hlaing had admitted in an interview aired on military-owned television he had not anticipated the level of civil unrest.

Campbell said Washington, which has imposed sanctions on the coup leaders and their economic interests, had supported efforts of the Association of Southeast Asian Nations and others to try to begin a process of moving Myanmar back to democracy and was urging countries isolate the generals diplomatically.

Popular

Wilmar executive, lawyers found guilty in $4 million palm oil bribery case

Analysis: Desperately seeking funds for Red and White cooperatives

Stocks set for tough week, oil eyes big gains as Middle East war rages