Rohingya Muslims remaining in Myanmar still face a "serious risk of genocide", UN investigators said Monday, warning the repatriation of a million already driven from the country by the army remains "impossible".

An army helicopter buzzes overhead and ambulances travel up wet empty roads in Myanmar's northeast, ferrying aid to thousands of residents displaced by fresh clashes between rebels and the military.

Burnt-out cars and bullet casings lie along the road to Shan state's Kutkai -- a town ringed by mountains, poppy fields, and a patchwork of ethnic armed groups fighting for more autonomy and control over land and resources.

Myanmar's military was Thursday fighting rebels who mounted an unprecedented strike at an army academy killing at least one, apparently in retaliation for massive drug seizures.

At least 22 people were killed when a landslide triggered by monsoon rains struck a village in eastern Myanmar, as emergency workers continued the search Saturday for scores more feared missing.

Two Reuters journalists who had been jailed for their reporting on the Rohingya crisis in Myanmar walked out of prison Tuesday, freed in a presidential amnesty after a global campaign for their release.

The deaths of three ethnic Rakhine men in Myanmar military custody and the secret cremation of their bodies has provoked outrage, as fears over military impunity increase in the intensifying conflict with Rakhine rebels.

A Myanmar court on Tuesday sentenced a prominent ethnic Rakhine leader to 20 years in jail for treason, a verdict likely to intensify anger amid fighting between the ethnic group and the army.

Panic is gripping thousands of Rohingya Muslim refugees living in no-man's land on the Myanmar-Bangladesh border, with daily clashes between Myanmar security forces and ethnic Rakhine insurgents.

The level of brutality used by Myanmar's military against the Rohingya minority is "hard to fathom", a UN investigator said Tuesday, presenting a damning report calling for top generals to be prosecuted for genocide.

A U.N. visit to Myanmar's conflict-battered Rakhine state was postponed Thursday, thwarting efforts to reach the epicenter of violence for the first time since the start of a massive exodus of minority Rohingya Muslims.