The 15-member council unanimously adopted a resolution promising to give political and economic aid if the Sudanese complete a final peace accord by Dec. 31.
U.N. officials hope the promise to reach an accord by year's end will also help quell a separate ethnic conflict in Sudan's western Darfur region, but warned against unwarranted optimism. Both sides have failed to fulfill three previous peace pledges in the past year, and negotiations to end the north-south war have stretched on for three years despite strong pressure from the United States and other governments.
U.S. Ambassador to the United Nations John Danforth, who has worked as a peace envoy to the region during much of the Bush administration, challenged the country's leaders to "prove the naysayers and skeptics wrong."
"We are keen, we are fully committed, to give the people of Sudan and to give Africa and the whole international community the gift of an agreement for the end of the year," Sudanese Vice President Ali Osman Taha told the Security Council.
John Garang, leader of the Sudan People's Liberation Army, the biggest southern rebel group, welcomed a resolution the council passed Friday demanding that the two sides sign a final agreement by Dec. 31.
"We will do our best to fulfill our commitment," he said.
"We are very close to peace, but we have been close before," said Danforth. "Do not let this opportunity slip away."
The civil war, Africa's longest running conflict, has pitted Sudan's Islamic-dominated government in the north against rebels seeking greater autonomy for the largely Christian and animist south. The conflict is blamed for more than 2 million deaths, primarily from famine and disease.
The accord signed Friday also called for an immediate halt to violence in the western province of Darfur, where Arab militias, known as the janjaweed and reportedly backed by the government, have terrorized black Africans since last year. The United States has labeled the actions of the militia genocide.
The U.N. resolution backing the peace accord says the council will consider "appropriate" actions if Sudan does not stop the war, suggesting it might impose sanctions. However China, a permanent member of the Security Council, has indicated that it would veto any action, while Russia, Algeria and Pakistan have also voiced opposition.
But human rights groups and aid agencies wanted the council to take stronger action on that conflict, complaining that a new national government would take months to start work, leaving the people of Darfur in limbo.
"From New York to Nairobi, a trail of weak resolutions on Darfur has led nowhere," Caroline Nursey of Oxfam International told Reuters.