The Southeast Asian country has been in chaos since last February's putsch, with a brutal crackdown on dissent and increased fighting in borderlands involving ethnic armed organisations.

Days after the coup, the junta reaffirmed a commitment to a ceasefire with the Arakan Army (AA), which has for years fought a war for autonomy for Rakhine state's ethnic Rakhine population.

On Friday junta troops entered an AA base in Maungdaw township, sparking three hours of clashes, a spokesperson for the group told AFP, adding one of its fighters had been killed.

"There is high tension militarily, which could break out any time," he said.

"It seems as if the military wants to destabilise Rakhine's stability and calm."

A junta spokesman said a number of border police had been killed in a mine attack on February 4, but blamed a local Rohingya insurgent group for the attack.

"We are still investigating the presence of the AA situation there," said spokesman Zaw Min Tun.

Clashes between the AA and the military in 2019 displaced more than 200,000 people across the state, one of Myanmar's poorest.

After the coup, the junta ended a 19-month internet shutdown in the state of around one million.

The AA previously reported its fighters had clashed with junta troops in November.

Rakhine state, home to both the Rohingya and a largely Buddhist ethnic Rakhine majority, has been a tinderbox of conflict for decades.

The military drove out more than 740,000 Rohingya Muslims from the state in a 2017 campaign that United Nations investigators have called genocide.

Rights groups have also accused soldiers of committing war crimes including extrajudicial killings in their later campaign against the AA.