The peace talks on Friday brought the Sudanese government together again with two rebel groups, the Sudan Liberation Movement (SLM) and the Justice and Equality Movement (JEM).
The heads of the two rebel groups - Muhammad al-Nur and Ibrahim Khalil respectively - were attending for the first time, while Agriculture Minister Majzoub al-Khalifa headed the government side.
AU commission head Alpha Oumar Konare opened the latest round of talks.
Konare, who had informal discussions beforehand with representatives of the Sudan government and the two rebel groups, said he hoped that "this phase of talks will be the last one".
The AU's chairman and host of the talks, Nigerian President Olusegun Obasanjo, appealed to all the warring parties to work towards peace in Darfur in a speech read on his behalf by government secretary Uffot Ekaette.
"No efforts should be spared by the parties in reaching agreement on the cessation of attacks, intimidation and other forms of violence against civilians," he said.
"All the parties must refrain from violence that could put in danger the lives of innocent civilians and abide by the agreements already entered into."
Obasanjo was out of Nigeria on a European trip, but expected back later on Friday.
"All the parties must refrain from violence that could put in danger the lives of innocent civilians and abide by the agreements already entered into"
Nigerian President and African Union chairman
AU special envoy to Sudan Salim Ahmad Salim hailed the delegates for their attendance, urging them to reach a consensus on issues before the talks.
"It is my hope that this session will be constructive. The decision on the part of the Sudanese parties in the conflicts to dialogue should be commended because it signals their determination to move the process forward," he said.
The Abuja peace talks which began in August 2004 were suspended in December to allow for more consultations among the parties who were accusing each other of violating the ceasefire agreements.