The United Nations announced Tuesday that it has appointed a Norwegian national as an interim resident coordinator in Myanmar and resident representative for the U.N. Development Program in the country.

Knut Ostby, who has served as a U.N. resident coordinator for more than 11 years, replaces Renata Lok-Dessallien in his new role, the U.N. said in a statement.

The announcement comes after more than 600,000 minority Rohingya Muslims have been driven out from Myanmar since late August amid a brutal crackdown by military security forces in northern Rakhine state. International humanitarian assistance, the U.N. and international media have not been allowed to enter the region, amid allegations of human rights abuses.

Lok-Dessalien has been criticized both by the U.N. and other international organizations for allegedly not effectively handling the human rights concerns in Rakhine. The U.N. statement said Lok-Dessalien will take another assignment at U.N. headquarters. U.N. Secretary-General Antonio Guterres said he was "grateful" for Lok-Dessallien's "important contribution and service" to the U.N.'s work in Myanmar.