The extension, announced earlier in the day, spelled a delay for elections the military had pledged to hold in August as it battles anti-coup fighters across the country.

"The United States is deeply concerned by the Burma military regime's extension of the state of emergency, which comes as the regime plunges the country deeper into violence and instability," said spokesman Matthew Miller, using an alternate name for the country.

The Southeast Asian country has been ravaged by deadly violence since a coup deposed leader Aung San Suu Kyi's government more than two years ago, unleashing a bloody crackdown on dissent that has sparked fighting across swathes of the nation while tanking the economy.

"Since overthrowing a democratically elected government two and a half years ago, the military regime has carried out hundreds of airstrikes, burned down tens of thousands of homes, and displaced more than 1.6 million people," Miller said.

"The regime's widespread brutality and disregard for the democratic aspirations of the people of Burma continue to prolong the crisis," he added.

"The United States will continue to work with our partners and allies to apply political and economic tools to hold the regime accountable."

Last month, Washington imposed sanctions on Myanmar's Defense Ministry and two "regime-controlled" banks, the state-owned Myanma Foreign Trade Bank and Myanma Investment and Commercial Bank