Sudan's government committed to a ceasefire in Darfur on Saturday at the start of UN-sponsored negotiations aimed at ending the 4 ½-year-old conflict, despite two main rebel groups refusing to attend the talks.

"The government of Sudan is proclaiming as of now a unilateral ceasefire in Darfur," Sudanese chief envoy Nafie Ali Nafie said at the talks in Sirte, Libya. "We shall not be the first ones to fire arms."

Jan Eliasson, UN special envoy to Darfur, talks to reporters ahead of the opening session of the Darfur peace talks in Sirte, Libya.
(Nasser Nasser/Associated Press)

The U.S. special envoy for Sudan, Andrew Natsios, praised the government for its pledge, but cautioned that dozens of previous ceasefire declarations in Darfur have been broken by both government troops and rebel factions.

The groups Justice and Equality Movement (JEM) and SLA-Unity announced Friday they would not attend negotiations after accusing the Sudanese government of inviting too many parties.

"The mediators adopted the policy of bringing every single individual and group, and all these groups and individuals were created by the Sudanese government," said Ahmed Tugod Lissan, JEM's chief negotiator.

The groups said they made the decision together because the Sudanese insisted the African Union and United Nations invite more than a dozen rebel factions, many described as small and insignificant.

Spokesmen for the boycotting factions said having so many players would make a unified rebel position at the talks impossible.

Despite the setback, Jan Eliasson, the UN special representative to Darfur, said the talks would go ahead.

"We have waited for a long time," Eliasson said. "The people of Darfur have waited for four and a half years. We saw no gain in delaying. Time is on nobody's side in Darfur."

The conflict in Darfur has claimed more than 200,000 lives since it started in 2003, pitting government-backed Arab militias against a largely ethnic African rebel movement.

Two million more people have been forced from their homes by the fighting.

A peace agreement achieved last year was also boycotted by some main rebel factions and the conflict has since grown worse, pushing more refugees into such neighbouring countries as Chad and the Central African Republic.

With files from the Associated Press