More than 65,000 Rohingya Muslims have fled Burma since a new flare-up in violence began, the UN has said, amid continued reports of the minority group suffering murder, rape and arson at the hands of the Burmese military.

A third of the refugees left in the last week alone as reports of the treatment of the Rohingya prompted a visit from the UN’s human rights envoy for Burma, Yanghee Lee.

The Burmese government denies any mistreatment of the Rohingya minority and, in an official commission's report, said there was no evidence of genocide or ethnic cleansing taking place.

The UN’s Office for the Coordination of Humanitarian Affairs announced the sudden rise in the refugees in its weekly report.

“Over the past week, 22,000 new arrivals were reported to have crossed the border from Rakhine state,” it said.

“As of 5 January, an estimated 65,000 people are residing in registered camps, makeshift settlements and host communities in Cox’s Bazaar,” in Bangladesh.

It comes after the Burmese military launched a crackdown in Rakhine state, where the majority of Rohingya live. Human rights groups have reported a series of abuses committed by soldiers but the Burmese government has denied the allegations.