UN Secretary-General Kofi Annan pressed African leaders to back peace in Darfur, saying the crisis threatened to spread instability beyond Sudan's borders if attacks on civilians were not stopped.
Speaking at an African Union summit in the Ethiopian capital Addis Ababa, Mr Annan told about 30 heads of state that conflicts including the crisis in western Sudan were holding back the 53-member union's struggle to defeat poverty and hunger on the continent of 830 million.
Un Secretary General Kofi Annan
"The vision you are working so hard to achieve is imperilled by the persistence of deadly conflict. I am thinking of the horrific situation in Darfur," said Mr Annan, who last week visited the region where more than a million people have been uprooted by conflict.
"The ruined villages, the camps overflowing with sick and hungry women and children, the fear in the eyes of the people, should be a clear warning to us all - without action, the brutalities already inflicted on the civilian population of Darfur could be a prelude to even greater humanitarian catastrophe - a catastrophe that could destabilise the region."
The Darfur crisis is seen by analysts and diplomats as a major test for the two-year-old AU, which is trying to win increased Western investment in return for ending wars and despotism and curbing corruption.
The AU is preparing to send hundreds of Nigerian and Rwandan troops to Darfur to guard an eventual 60 AU peace monitors as well as to patrol refugee camps and border areas between Sudan and Chad, where some 200,000 Sudanese have fled to safety from attacks by Arab militias. Sudan reluctantly agreed to the deployment.
The AU has already sent unarmed observers to Darfur.
But despite pressure from the AU, the United Nations and the United States, the path to peace in Darfur looks uncertain with two rebel groups saying they would not negotiate unless Sudan first disarmed the marauding Arab militias known as the Janjaweed and respected a shaky ceasefire agreed in April.