Sudan ordered at least 10 humanitarian groups expelled from Darfur on Wednesday after the International Criminal Court issued an arrest warrant for the country's president.
Secretary-General Ban Ki-moon said the action "represents a serious setback to lifesaving operations in Darfur" and urged Sudan to reverse its decision, U.N. deputy spokeswoman Marie Okabe said.
Aid groups protested, saying they had no connection to the court and that their absence could lead to a crisis for hundreds of thousands of war-weary Sudanese who need such basics as shelter, food and clean water.
"It is absurd that we as an independent organization are caught up in a political and judicial process," the operational director of Medecins Sans Frontieres Holland, Arjan Hehenkamp, said in a statement.
Sudan's order was announced after the International Criminal Court issued an arrest warrant for President Omar al-Bashir on charges of war crimes and crimes against humanity in Darfur.
Sudanese Vice President Ali Osman Mohammed Taha confirmed that 10 "associations" were asked to stop operating "because they violated laws and regulations."
"Whenever an organization takes humanitarian aid as a cover to achieve a political agenda that affects the security of the county and its stability, measures are to be taken by law to protect the country and its interests," he said.
The non-governmental aid groups ordered out were Oxfam, CARE, MSF-Holland, Mercy Corps, Save the Children, the Norweigan Refugee Council, the International Rescue Committee, Action Contre la Faim, Solidarites, and CHF International.
Okabe said the groups were informed by the Sudanese government's Humanitarian Aid Commission that their legal registrations have been revoked, were given a list of assets for seizure and told they must leave north Sudan, which includes Darfur, "with immediate effect."
"Affected NGOs are the main providers of lifesaving humanitarian services, such as water, food, health and sanitation" in the region, she said.
The war in Darfur began in 2003 when rebel groups took up arms against the government, complaining of discrimination and neglect. U.N. officials say up to 300,000 people have died and 2.7 million have fled their homes. Many live in camps which NGOs help run.
"If Oxfam's registration is revoked, it will affect more than 600,000 Sudanese people whom we provide with vital humanitarian and development aid, including clean water and sanitation on a daily basis," Penny Lawrence, Oxfam's international director, said in London. Oxfam said it is appealing the order to leave.
Save the Children UK said it is helping about 50,000 children affected by the Darfur conflict.
"We don't know what the outcome of these developments will be, but we do know that if we are forced to stop our work, the lives of thousands of children could be at risk," said Ken Caldwell, the charity's director of international operations.
Vanessa Van Schoor, Sudan operations manager for MSF Holland, said the group was told several days ago "to pull out of our field projects."
The expulsion only applies to the Dutch section of MSF, which had 27 international staff and around 520 national staff in Sudan, Van Schoor said.
It was not clear whether those terms apply to the other aid groups told to leave Sudan.