Authorities in war-hit Sudan have declared the head of the United Nations mission in the country, Volker Perthes, “persona non grata” two weeks after the army chief accused him of inflaming the conflict and called for his removal.

“The Government of the Republic of Sudan has notified the Secretary-General of the United Nations that it has declared Mr Volker Perthes … persona non grata as of today,” Sudan’s Ministry of Foreign Affairs said in a statement on Thursday.

Sources at the ministry told Al Jazeera that the mission itself will be allowed to continue its work.

“Some of their staff [are] in the port city of Port Sudan, where most of the mission were evacuated to following the fighting that broke out in mid-April between the Rapid Support Forces [RSF, a paramilitary group] and the Sudanese army,” said Al Jazeera’s Hiba Morgan, reporting from Omdurman, a city across the Nile from the capital, Khartoum.

The United Nations responded later on Friday, saying that UN personnel cannot be made persona non grata.

“The Secretary General recalls that the doctrine of persona non grata is not applicable to or in respect of United Nations personnel and its invocation is contrary to the obligations of states under the Charter of the United Nations,” UN spokesman Stephane Dujarric said.

He added that Perthes is currently in Addis Ababa.

UN chief Antonio Guterres said late last month that he was “shocked” by the letter from Sudanese army chief Abdel Fattah al-Burhan blaming Perthes for exacerbating fighting between the army and the RSF, led by commander Mohamed Hamdan “Hemedti” Dagalo.

“[Guterres] is proud of the work done by Volker Perthes and reaffirms his full confidence in his special representative,” UN spokesperson Stephane Dujarric said in a statement at the time. There was no immediate UN reaction to the foreign ministry’s declaration.