The Sudanese government and rebel officials signed the last two components of a comprehensive peace deal to end a 21-year war in southern Sudan, with officials warning that implementing the deal could be as hard as negotiating it.
Diplomats suggested the deal's many protocols, signed over two years of peace talks, could also help advance negotiations to end another conflict in Sudan's western region of Darfur. But a Darfur rebel said that was unlikely.
The government and southern rebel officials signed a permanent ceasefire deal on Friday and endorsed a detailed plan on implementing agreements to end what has been one of Africa's longest-running wars.
The deals clear the way for the two sides to sign a comprehensive peace deal in early January in the Kenyan capital of Nairobi.
"Negotiating this agreement has been difficult. Implementing it is going to be every bit as difficult," US Ambassador William Bellamy said.
Southern Sudan has no modern roads and few basic amenities after decades of war between the Islamic-dominated government and mainly animist rebels seeking more autonomy and a greater share of the country's wealth. The conflict is blamed for more than two million deaths, mostly from war-induced famine and disease.
The ceasefire comes into force about 72 hours after being signed on Friday, said Sayed El-Khatib, spokesman for the Sudanese government delegation at the talks.
The two sides also signed agreements on Friday on how to implement protocols on sharing power and wealth, what to do with their armed forces during a six-year transition period, and how to administer three disputed areas in central Sudan.
"We now have all the components that will form the comprehensive Sudan peace agreement," said chief mediator Lazaro Sumbeiywo, a retired Kenyan general.
Sudan's Vice President Ali Osman Mohammed Taha promised "to ensure we will be their [the Sudanese] servants to implement the agreements we've signed."
"We have kept our promise," made last month to sign a peace deal by year's end, rebel leader John Garang said.
UN Secretary-General Kofi Annan welcomed the agreements on Friday, saying he looked forward to January's final comprehensive deal "ushering in a new era of peace in Sudan, in which the United Nations is prepared to play a significant role," according to a statement.
Annan is to report on the deal to the UN Security Council in two weeks, after which the council should mandate a peace support mission to monitor the southern ceasefire and help the government and rebels reduce and relocate their forces, said Taye-Brook Zerihoun, Annan's special envoy to Sudan.
"They have a tremendous task ahead in the area of governance ... In the establishment of functional institutions in the south and the challenge of making national institutions work," Zerihoun said.
South African President Thabo Mbeki witnessed the signing of the deals with Sudanese President Omar el-Bashir and Kenyan Vice President Moody Awori.
Sudan's next immediate task should be to resolve the separate crisis in Darfur, the US ambassador said.
"Tomorrow, everybody who is celebrating here needs to work on Darfur," Bellamy said.
Other international officials suggested the deal with southern Sudan could provide the government with a framework for peace negotiations with Darfur.
"It would provide a way for the government to address other conflicts in the Sudan, including Darfur," Zerihoun said.