Myanmar's military have been accused of committing "crimes against humanity" after their treatment of the Rohingya Muslim minority.

Amnesty International's latest report on Monday accuses the mainly Buddhist Burmese forces of murder, rape, torture and looting in the northern Muslim-majority state of Rakhine.

Myanmar's military have denied the allegations and said it is merely fighting terrorists.

But the 'We are at breaking point' report by the human rights charity documents a "campaign of violence" against the persecuted Muslim minority.

"Soldiers and police have randomly fired on and killed civilians, raped women and girls, torched whole villages and arbitrarily arrested Rohingya men without any information about their whereabouts or charges," the report's summary read.

"These actions have been a form of collective punishment targeting Rohingya in northern Rakhine state, and may amount to crimes against humanity."

The report comes after a separate UN official said Myanmar was conducting "ethnic cleansing" against the Rohingya.

Amnesty said at least 27,000 have fled to neighboring Bangladesh since October, putting the already impoverished country under heavy strain.

But many refugees are also turned away at the border, the report said.

The Rohingya are largely seen as illegal immigrants in the Buddhist-majority Myanmar, also called Burma.

Aung San Suu Kyi, who won the country's first credible elections in 25 years in 2015, has defended the actions of her army. She has accused the international community of stoking resentment by highlighting the issue.

The report comes at the same time as a highly unusual meeting of Asean, the 10-nation regional body representing South East Asia, in Yangon.

In a rare move the body will discuss affairs in Myanmar after months of criticism over the violence.