UN Humanitarian Air Service or UNHAS cancelled many flights because it did not receive Flight Safety Assurance for all locations.
The humanitarian airline announced to users on Tuesday that authorities continue to delay permission to UN aircraft to some parts of South Sudan.
The Airline informed its clients that Upper Nile region is among the areas most affected.
Flights to Wau, Aweil, Yambio, Rumbek and Kapoeta are expected to continue normally, it clarified.
The Air service added that flights to all other destinations for the coming days will depend on clearances.