Amnesty International has said satellite images of burnt villages in Rakhine state show Myanmar's security forces have led "systematic" clearances of Rohingya Muslim settlements over the past three weeks.

At least 26 villages have been hit by arson attacks in the Rohingya majority region, the rights group said, with patches of grey ash picked up in photos marking the spot where homes had once stood.

Amnesty said fire sensors also deployed on satellites had detected 80 large-scale blazes across northern Rakhine state since 25 August, when the army launched "clearance operations" in response to attacks by Rohingya militants.

"Rakhine state is on fire," said Olof Blomqvist, a researcher with Amnesty International, in a "clear campaign of ethnic cleansing by the Myanmar security forces".

The group quoted Rohingya witnesses who described security officers and vigilantes using petrol or shoulder-fired rocket launchers to set homes alight, before firing on villagers as they fled.

In some ethnically mixed communities, such as the village tract of Inn Dinn, images showed that only Rohingya homes had been burned, the report said.

"It's very difficult to conclude that it is anything other than a deliberate effort by the Myanmar military to drive Rohingya out of their own country by any means necessary," Mr Blomqvist added.

Myanmar denies targeting Rohingya, instead insisting the militants have set the fires.

The Myanmar government says nearly 40% of Rohingya villages are now empty in the northernmost part of Rakhine, but argues not all have run from army operations, insisting some were either linked to the "extremist terrorists" or scared of them.

But scores of Rohingya refugees have detailed raids by soldiers who fired on civilians before razing entire communities, often with the help of ethnic Rakhine Buddhist mobs.

The accounts from Amnesty matched a flood of testimony collected by AFP in refugee camps along the Bangladesh border.

"There is a clear and systematic pattern of abuse here. Security forces surround a village, shoot people fleeing in panic and then torch houses to the ground," said Tirana Hassan, Amnesty's crisis response director.

"The government's attempts to shift the blame to the Rohingya population are blatant lies," she added.