The Sudanese government declared a cease-fire at the start of the U.N./African Union-mediated talks on Saturday, but rebels said Monday that government forces were still attacking an area along the western border with Chad.
"At the same time they were announcing that there is a cease-fire, there was aerial bombardment in Jabel Moun," said Justice and Equality Movement commander Abdel Aziz el-Nur Ashr.
A Sudanese army spokesman denied the report. "We have no government forces there and it is not in our benefit to bomb anyone," he said, according to Reuters.
The talks were the first attempt to gather Darfur rebels and government representatives around the negotiating table since AU-brokered talks in Abuja, Nigeria, in 2006. One rebel group participated in those talks.
The power-sharing deal brokered in Abuja earned little support among the 2 million Darfur refugees and the rebel movement splintered into at least a dozen factions, causing more violence to ensue.
International mediators emphasized that the weekend's talks in Libya were a starting point for what will likely be a long process of negotiations, and they said they hoped to convince boycotting rebel groups to eventually participate.
The U.N. and AU representatives continued closed-door discussions with the Sudanese delegation and six rebel groups, saying the low-level talks in the city of Sirte were part of a preliminary phase that would lead to more substantial talks.
"Only after that period ... of approximately three weeks, will we go into substantial negotiations," U.N. chief mediator Jan Eliasson told the Associated Press.
Factors hindering an agreement include the inability among the rebel factions to agree on their own negotiating terms and the lack of security in the country.
The United Nations and African Union are scheduled to deploy about 26,000 peacekeepers to Darfur in January. Currently, about 7,000 AU forces are in the region.