Myanmar's junta has reported "heavy assaults" by insurgents and told government staff to get ready for emergencies, an official said on Thursday, while media reported a call for those with military experience to prepare to serve.

Myanmar's military has battled ethnic minority and other insurgencies for decades, but a 2021 coup has brought unprecedented coordination between anti-military forces that are mounting the biggest challenge to the army in years.

Junta spokesperson Zaw Min Tun said the military was facing "heavy assaults from a significant number of armed rebel soldiers" in Shan state in the northeast, Kayah state in the east and Rakhine state in the west.