United Nations secretary general Ban Ki-moon has proposed a new mission for South Sudan after it becomes independent on July 9, requesting 7,000 troops to protect civilians and a mandate to help the new government prevent conflict and keep the peace.
Mr Ban's proposal in a report to the Security Council was circulated as the UN's most powerful body was visiting Sudan.
But it was written before serious fighting erupted last week in the disputed oil-rich Abyei region on the border between the Arab-dominated north and mainly-ethnic African south. The clashes threaten to unravel a 2005 peace deal that ended more than two decades of civil war and reignite the fighting.
The south voted overwhelmingly to secede from Sudan, Africa's largest country, in a January referendum called for under the peace agreement. But key provisions of the 2005 agreement have not been resolved.
The secretary general called the dispute over the future status of Abyei "the greatest challenge" to implementing the peace accord.
He urged leaders from both sides to demonstrate "political will" and solve key issues including setting the north-south borders, resolving Abyei's future through the referendum called for in the peace agreement, and agreeing on security arrangements.
Mr Ban said the best way was through the framework established in the 2005 agreement until an alternative arrangement was found. That framework includes the only forum for the parties to meet, under UN auspices, to prevent or mitigate conflict on either side of the border, including Abyei.
"I therefore cannot stress enough the critical nature of these negotiations and the responsibility that rests on the leaders of the two states to reach agreements that will provide the foundation for peace and security in the Sudan and South Sudan and the region as a whole," the secretary general said.
The government of South Sudan has asked for the UN to establish a follow-up mission after the current mandate expires on July 9, but the government in Khartoum has not.
Mr Ban urged the north and the south, and the security council, to consider extending the mandate of the current 10,400-strong UN peacekeeping mission for three months, from July 9 to October 9.