The United Nations has appointed a Norwegian as an interim resident coordinator in Burma and resident representative for the UN development programme in the country.
Knut Ostby, who has served as a UN resident coordinator for more than 11 years, replaces Renata Lok-Dessallien in his new role, the UN said in a statement.
The announcement comes after more than 600,000 minority Rohingya Muslims have been driven out from Burma since late August amid a brutal crackdown by military security forces in northern Rakhine state.
International humanitarian assistance, the UN and international media have not been allowed to enter the region, amid allegations of human rights abuses.
Ms Lok-Dessallien has been criticised both by the UN and other international organisations for allegedly not effectively handling the human rights concerns in Rakhine.
The UN statement said Ms Lok-Dessallien will take another assignment at UN headquarters.
UN secretary-general Antonio Guterres said he was "grateful" for Ms Lok-Dessallien's "important contribution and service" to the UN's work in Burma.
Meanwhile, a boat carrying up to 45 Rohingya Muslims fleeing Burma has capsized in the Bay of Bengal, and a Bangladeshi official said four bodies were recovered.
It was not clear how many people were missing.
Mohammed Mikaruzzaman, local government administrator at Ukhiya, said some 23 people were rescued and a dozen of them were being treated.
The boat capsized on Tuesday morning near Inani beach in Cox's Bazar district, which borders Burma.
The UN refugee agency said survivors told its staff that 42 people from six families left on a fishing boat in Burma's northern Rakhine state early on Tuesday.
The boat hit rough seas and capsized, trapping people underneath, the agency said.
More than 600,000 Rohingya Muslims have reached refugee camps in Bangladesh since Burma's security forces launched operations on August 25 that the United Nations and others have described as "ethnic cleansing".
About 190 people trying to flee have died in boat accidents in the Bay of Bengal or nearby waterways.