Myanmar junta troops have moved back into a vital border town they were ousted from by an alliance of ethnic rebels and anti-junta fighters this month, military sources told AFP Tuesday.

The Karen National Union (KNU) and "People's Defence Force" fighters ousted around 200 military soldiers from their positions in the lucrative trade hub of Myawaddy around April 10, in a major blow to the junta.

The troops withdrew to a bridge that connects Myawaddy to Thailand's Mae Sot town following the clashes, which sent thousands fleeing Myanmar.

On Tuesday "some of our troops arrived at the 275 military command," junta spokesperson Zaw Min Tun told AFP, referring to the previously vacated military base in Myawaddy.

He said the military still did not have "complete control" of Myawaddy and did not say if there had been fighting in the town on Tuesday.

He said there had been "casualties from both sides in previous fighting," without giving further details.

AFP has asked a KNU spokesperson for comment.

A Myawaddy resident said that the town appeared quiet on Tuesday.

Another military source, who requested anonymity as they were not authorised to talk to the media, told AFP troops had retaken the 275 base on Tuesday.

The military has carried out airstrikes around Myawaddy in recent days, according to residents, and has sent reinforcements towards the town.

Fighting was ongoing around the town of Kawkareik, which sits on the route to Myawaddy, according to Zaw Min Tun.

The military now controls the town itself, he said.

The Karen State Border Guard Force, a local military-aligned militia that controls much of Myawaddy, announced this year that it would no longer take orders from the junta.

It is not clear what role it played in the recent fighting around Myawaddy.

AFP was unable to reach the group for comment.

The conflict in Myanmar sparked by the military's 2021 coup regularly sends people fleeing across the 2,400-kilometre (1,490-mile) border with Thailand.

Thailand's foreign minister visited Mae Sot on Tuesday and called for an end to the clashes.

The junta came to power in the February 2021 coup that ousted Aung San Suu Kyi's elected government, ending an experiment with democracy and plunging the Southeast Asian nation into turmoil.

The putsch sparked renewed conflict with ethnic rebel groups and birthed dozens of newer "People's Defence Forces" that analysts say have surprised the military with their effectiveness.

The fighting has displaced more than 2.5 million people, according to the United Nations.