The senior UN representative in Burkina Faso has been told to leave right now.
Barbara Manzi was designated "persona non grata" by the military government.
The UN official's recent warnings of coming turmoil brought on by the Islamist insurgency, according to Foreign Minister Olivia Rouamba, have damaged Burkina Faso's reputation and turned away potential investors.
Within a year, the insurgency prompted two military coups and forced over two million people to flee their homes.
Many of the displaced people reside in UN-run camps.