There has been a warm welcome for Sudan's peace deal paving the way for an end to Africa's longest-running war.
Scenes of jubilation greeted the signing in Kenya
But concerns are being raised that there will be no peace until a separate conflict in the Darfur region is ended.
Joy and relief met the signing of key deals ending months of wrangling between the Islamic government and Christian and animist rebels.
An estimated two million people have died in the war, which erupted between the north and south in 1983.
There were scenes of jubilation at the signing in Naivasha, Kenya, late on Wednesday evening as last-minute delays were overcome after two years of discussions.
US Secretary of State, Colin Powell, praised the agreement and urged the two sides to work out quickly how to implement it but added a warning about the fighting in western Sudan.
"Sudan will not be at peace until the problem of Darfur is resolved," he said.
United Nations Secretary General, Kofi Annan, described the agreement as a major step forward and said the UN was ready to help put it into practice.
'No more hills'
The deal involved protocols on power-sharing and the administration of three disputed areas in central Sudan.
The Sudan People's Liberation Army (SPLA) leader John Garang said: "We have reached the crest of the last hill in our tortuous ascent to the heights of peace. There are no more hills ahead of us,
the remaining is flat ground."
Sudan's Vice President, Ali Osman Taha, expressed equal determination to make the deal work.
"It's our duty in Sudan to put these words into action with the same degree of determination to make peace," he said.
A major rally is being held in Khartoum later on Thursday.
The framework brings together the mainly Muslim Arab government of the north with the black African Christian and animist rebels of the south.
Hundreds of Sudanese and Kenyan officials and foreign diplomats, including US Acting Assistant Secretary of State for African Affairs Charles Snyder, were kept waiting for several hours as the signing ceremony in the Kenyan lakeside resort of Naivasha was delayed for several hours.
Talks had stalled on how power would be shared in a transitional administration; on whether the Sudanese capital, Khartoum, would be governed under Islamic law; and how Abyei, the Nuba Mountains and Southern Blue Nile regions would be administered.
In the end, it was agreed that the north would have 70% of jobs in the central government, with 30% filled by southerners.
In the three disputed regions, the government will have 55% of the positions and the rebels 45%.
The two sides have already established that the south should be autonomous for six years, culminating in a referendum on the key issue of independence, with Sharia law remaining in the north.
Protocols have also been signed on how to share out oil revenues, the establishment of separate monetary systems in the north and south, and security arrangements involving the two armies.
All that remains for the two sides to work out are procedural matters to end the 21-year civil conflict.
It is hoped that a final peace treaty could be signed in Washington as early as next month.
The US said the deal paved the way for normal relations to be revived with Sudan, providing certain conditions were met.
But the fanfare witnessed at the signing in Kenya has not been seen across Sudan itself.
The BBC's Alfred Taban in Khartoum says southern Sudanese were happy about the deal, but those in the north are more concerned about the situation in the troubled western Darfur region.
"They feel the problems in Darfur are getting worse so how can they celebrate victory in the south," he told the Network Africa programme.
Sudan analyst Gill Lusk says the arrival of peace in the south has enabled the government to switch military resources to Darfur.
Black Africans in the region say Arab "Janjaweed" militias are chasing them from their homes and are working with government forces.
Some one million people have fled since the conflict began in February 2003.
The international monitoring group, Human Rights Watch, said the peace deal was a huge step forward, but came as the Sudanese government have been taking a terrible step backward in Darfur.
It said Khartoum was carrying out a campaign of ethnic cleansing in the region, which raised questions about whether it was really willing to comply with the agreement for the south.