The U.N. Security Council failed to act with a unified voice Friday, during a meeting about the fragile humanitarian situation in the Darfur region of Sudan. Khartoum has vowed to expel several of the largest international aid organizations assisting over four million displaced persons there. The U.N. has warned that the action will have immediate effects, and that as soon as Monday, thousands of residents of at least one camp for displaced persons could be without clean water and sanitation.

Diplomats said there was deep concern among the 15 Security Council members about the expulsion of the aid organizations and the impact it could have on the humanitarian situation, but they were unable to translate that into a formal statement.

"There was a lot of concern around the council table about this decision; about the impact it was going to have on ordinary people in Sudan, and about the inability of any organization - the U.N. or Sudanese organizations or regional organizations - to fill the gapping hole left by the expulsion of these NGOs," said British Ambassador John Sawers spoke to reporters.

Sudan revoked the licenses of 13 international aid organizations on Wednesday, after the International Criminal Court issued an arrest warrant for Sudanese President Omar al-Bashir for atrocities committed in Darfur. Khartoum accuses the groups of giving evidence to the court, a charge the charities deny.

U.S. Ambassador Susan Rice expressed the Obama administration's "grave concern" over the action during a telephone conference call with reporters. She said Washington is working with others to try to reverse what she called Sudan's "reckless decision."

The U.N. says the affected aid groups, which include Oxfam, Save the Children and Doctors Without Borders, are responsible for at least half of the humanitarian capacity in Darfur, and that if this order stands, an already fragile living situation could worsen.

U.N. deputy emergency relief coordinator Catherine Bragg briefed the council. She said the Kalma camp, which is home to some 90,000 displaced persons, could be among the first to feel the effects. "The Kalma camp is a very dire situation because the NGOs that are providing water and sanitation to that camp are amongst those being expelled. We are looking at the possibility that come next week we will have difficulty of providing water and sanitation in that camp," she said.

She also said she insisted to the council that the humanitarian situation should be separated from any discussion or debate about the ICC decision.

Bragg added, that if Sudan does not reverse the expulsion order, the number of affected people could reach the millions.