Government forces used artillery to flush out rebels from the western town of Mindat after fighting broke out on May 12, a spokesman for a local insurgent group said, and later cut off its water supply.

One resident who did not want to be named told AFP that most of those who had been trapped in the town by the fighting had now fled, but those left behind faced a grim struggle for basic supplies.

"All the people rely on a government pipe for their water supply... in these conditions we have to stop washing if we want to be able to cook," the resident told AFP.

The fighting around Mindat between the Chinland Defence Force and the Myanmar military has likely displaced "thousands" of civilians, the United Nations Office for the Coordination of Humanitarian Affairs said Tuesday.

"Access by humanitarian partners to the people fleeing violence or those still in their homes is challenging due to insecurity," it said, adding it had received reports civilians had been killed in the fighting.

"We have been constantly helping the people from the town to relocate to the remote villages," another resident told AFP.

"They need... a safe zone recognised by international organisations like the UN."

Myanmar has been in uproar since the military ousted civilian leader Aung San Suu Kyi in a February 1 coup, triggering a massive uprising which authorities have sought to quell with lethal force.

Some in the anti-junta movement have set up local militias armed with homemade weapons to protect their towns from security forces -- which have killed more than 800 people according to a local monitoring group.

A CDF spokesman, who declined to be named, told AFP that fighters had set fire to several army trucks, destroying them, and ambushed reinforcement troops during the fighting in Mindat.

Photos released later by the group purported to show weapons and trucks seized from the military in an ambush.

With mobile data blocked across the country, details about the fighting have been slow to come out, and on-the-ground verification is made harder as locals are fearful of retaliation.