The Sudanese government committed to an immediate cease-fire Saturday at the opening of new Darfur peace talks, but the expected announcement was not met by similar pledges from rebels, who had largely decided to boycott the U.N.-brokered negotiations.

"The government of Sudan is proclaiming as of now a unilateral cease-fire in Darfur," said Nafie Ali Nafie, who was heading an important Sudanese delegation to the talks in the Libyan coastal town of Sirte. "We shall not be the first ones to fire arms."

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

Sudan's announcement, which the government had previously pledged to make, came as negotiators moved to lower expectations for the talks, which are geared at ending over four years of fighting that have killed more than 200,000 people in Sudan's western region of Darfur.

With no major rebel players, however, hopes faded for Sirte to see a quick peace agreement and mediators played down the conference's goals, insisting that focus would now be to "create conditions" for effective peace talks to take place.

They said negotiations will also give a larger role to groups representing civilians, which have had little say so far.

"We are going to try very hard to create a framework for the talks," conference spokesman Ahmed Fauzi said, warning this would be "a long process."

Immediately after the talks were announced, Adulwahid Elnur, the founder of the Sudan Liberation Army rebels, said he would boycott until the U.N. and African Union have deployed a joint force of 26,000 peacekeepers due in January.

Khalil Ibrahim, the leader of the rival Justice and Equality Movement, had initially agreed to the talks, but just on Friday announced he was also boycotting because the U.N. were inviting smaller, less representative rebel factions to attend.

JEM and the main SLA groups say the smaller factions attending are just stooges for the Sudanese government. The U.N. and AU mediators say they tried to invite everybody so that negotiations were as inclusive as possible.

Mediators did not know exactly how many rebel factions to expect at the talks, but the chief U.N. mediator, special envoy Jan Eliasson, said six or seven groups could be there by Saturday. "People keep coming, there's a slow trickle," he said.

The talks' first priorities are to reach an immediate cease-fire, discuss the return of Darfur refugees to their destroyed villages, and obtain financial compensations for war victims, Eliasson said.

"I hope (the government) will show a generous and positive attitude toward this," Eliasson said.

He insisted several midlevel rebel commanders intended to join the talks within a week or so, once their groups have organized negotiation teams.

The U.N. was still trying to locate several commanders who want to be flown out of Sudan to join the talks in the Libyan coastal town of Sirte, said spokesman Fauzi. "We have faced important political and logistical difficulties."

Clearly in evidence at Sirte, though, were large international delegations which came to be briefed by the U.N. and AU on what could be done to build a future framework for talks.

"My presence here is a sign of a more active role for the Arab League" in helping resolve Darfur's conflict, league Secretary General Amr Moussa told The Associated Press ahead of the talks.

Egypt, the regional heavyweight, has been criticized for not putting more pressure on its southern neighbor to end the violence. But Foreign Minister Ahmed Aboul Gheit said his government would do its "best to help with a cease-fire and to encourage those who aren't here to attend."

"We know the (Sudanese) government, I've met most of the rebels, we're in touch with everybody," Aboul Gheit said, voicing hope a solid peace would eventually be achieved. "But we know it's a hard job."

Darfur's ethnic African rebels took arms in 2003 against the Arab-dominated central Sudanese government, accusing it of decades of discrimination. The government is accused of retaliating with mass violence against civilians that has killed more than 200,000 and made over 2.5 million refugees, largely ethnic Africans.

Libyan leader Moammar Gadhafi officially opened the talks Saturday. His increased role in the peace effort is viewed as a pledge by Libya to show it has ended decades of international isolation and can play its part in regional diplomacy.

But many rebels have grown skeptical of the Arab states' involvement in the peace process, stating they are biased toward Khartoum.

Elnur, the SLA chief, said he would refuse any talks in Libya because it was involved for over a decade in fighting in Darfur and neighboring Chad.