The United Nations wants the Sudanese government to allow peacekeepers to remain in place as the south prepares to celebrate its independence, officials say.
South Sudan becomes the world's newest nation Saturday.
Sudanese President Omar al-Bashir and dignitaries from around the world will attend celebrations commemorating the event, the BBC reported Friday.
More than 99 percent of the south voted to secede from the north as part of a 2005 deal to end 20 years of civil war in which about 1.5 million people died.
"It's vital that the United Nations be allowed to maintain a full peacekeeping presence in these areas for an additional period of time," said Susan Rice, United States U.N. ambassador.
The United States called on Bashir's government to allow U.N. peacekeepers to remain in the north after Sudan threatened to expel them from South Kordofan and Blue Nile.
Bashir said he wants the new country to be "secure and stable."
"We will bless our brothers in the south over their country and we wish them success," Bashir said.
Sudan and South Sudan must still decide on drawing up a new border and how to divide Sudan's financial obligations and oil wealth. Most of Sudan's oil is in the south.