The United Nations has promised aid to Sudan's government and southern rebels if they fulfil a promise to finalise a peace deal by the end of the year.
The SPLA rebels have agreed to give up their armed campaign
The Sudanese parties signed the pledge at a special UN Security Council meeting in Kenya.
The council adopted a resolution backing the commitment. It also called for an immediate end to violence in the western Sudanese region of Darfur.
But aid agencies said the resolution was weak and urged further action.
New Year deadline
An estimated two million people have been killed since the civil war in southern Sudan began 21 years ago.
The peace pledge was signed on Friday by a
Sudanese government official and a representative of the rebel Sudan People's Liberation Movement, witnessed by UN Security Council ambassadors.
The memorandum said: "The parties recommend themselves to finalise and conclude a comprehensive peace agreement in recognition that prompt
completion of the peace process is essential for all the people
of the Sudan as it will help in resolving all challenges facing
It said the peace deal should be signed no later than 31 December 2004.
The BBC's Susannah Price in Nairobi says the UN wanted, and got, a unanimous vote for its resolution, to send the strongest possible signal to the government and the southern rebels.
The Security Council's meeting in Nairobi is only the fourth time it has met away from UN headquarters in New York.
Although its resolution focuses on the north-south peace accord, it also expresses grave concern about the violence in Darfur.
It urges the government, the rebels and all armed groups to stop the violence, and says the Security Council would monitor compliance.
UN Secretary General Kofi Annan has said he hopes an agreement in the south will prepare the ground for a solution in Darfur.
The council's president, US ambassador John Danforth, said the resolution proves the UN "takes the situation of Darfur seriously".
But aid agencies said diplomatic statements were not enough.
The council has already passed two resolutions threatening sanctions if Khartoum does not disarm the pro-government militias in Darfur, but aid agencies and human rights groups say the violence is continuing.
"From New York to Nairobi a trail of weak resolutions on Darfur has led nowhere," said Caroline Nursey of the UK-based charity Oxfam.
"Yesterday Oxfam was unable to get vital aid to 200,000
people in Darfur who are cut off by renewed violence... We needed the council to take action now, not yet
more diplomatic dithering."
The civil war in Darfur there broke out in early 2003, when rebel groups began attacking government targets, saying the government had neglected the region.
In response Khartoum mobilised Arab "self-defence militias", which are accused of carrying out atrocities against local black Africans.