South Sudan authorities ordered Norwegian Refugee Council Area Manager in Alek of Warrap State to leave the country on Tuesday.
The Council is deeply dismayed about the order for a second senior staff to leave in less than a week without formal explanation of the charges against the two individuals.
The order for a second senior staff member to leave is unacceptable, said Jan Egeland, Council Secretary-General in a statement.
Aid organizations must be permitted to operate without interference, intimidation or fear of expulsion to bring relief to people of South Sudan, he added.
The Secretary-General called for respect of humanitarian laws and that ordering aid workers to leave without due process restricts the ability of relief agencies to reduce suffering.
Egeland called for assurances from the authorities to operate without interference because aid organizations cannot operate in difficult conditions.
From January to August this year alone, organization provided humanitarian assistance to over 658 thousand people across the country, he recalled.