The United Nations says the government of Sudan has effectively expelled a top U.N. official in charge of coordinating relief efforts there.

U.N. Spokesman Stephane Dujarric said Monday that Sudan's Ministry of Foreign Affairs has refused to renew the annual stay permit for Ivo Freijsen, who heads the Office for Coordination of Humanitarian Affairs, without providing an official explanation.

Dujarric said that while Freijsen was not declared a persona non grata, refusing to renew his visa represented "a de facto expulsion." He added that the U.N. was doing its best "to get the situation reversed."

In 2015, the U.N.'s humanitarian team and its partners in Sudan were responsible for coordinating and delivering over $600 million in aid to hundreds of thousands of people across the country.