"These abhorrent attacks underscore the urgent need for the international community to hold the Burmese military accountable and take action to prevent gross violations and abuses of human rights, including by preventing the transfer of arms to the military," State Department spokesman Ned Price said in a statement, using Myanmar's previous name.

On Friday, local media and witnesses reported that junta troops had shelled the town of Thantlang after a confrontation with a local self-defense force.

A fire then engulfed the town, destroying dozens of homes and structures -- including a Save the Children office, the London-based charity confirmed in a statement.

Most of Thantlang's inhabitants had fled the town during clashes last month, many of them crossing the border to India.

The junta's information team confirmed Saturday that two churches and 70 homes were burnt down in the town, but accused the local "people's defense forces" of the blaze, after security forces had clashed with their fighters.

Junta spokesman Zaw Min Tun telling local media the military's role in Thantlang's razing was "groundless accusations."

AFP could not independently verify the reports from the remote region.

Price said Washington also expressed concern over the "intensification of military operations" by the junta throughout the Southeast Asian country, which has been plunged into chaos since a February coup, with more than 1,200 people killed as nationwide military cracks down on dissent.

So-called "people's defense forces" (PDF) have sprung up across the country to take on the junta, escalating attacks and bloody reprisals.

The United Nations said last week it feared a wider human rights catastrophe amid reports of thousands of troops massing in the north and west of the country.

In May, government forces used artillery to flush out rebels from the town of Mindat in the southern part of Chin state, and later cut off its water supply, according to a spokesman for a local insurgent group.