Sudanese government officials and Darfur rebels will meet privately on Monday to discuss an agenda for peace talks but delegates said little real progress was expected in the absence of key rebel leaders.

Declaring the two-day opening session of the talks closed, U.N. envoy Jan Eliasson added in remarks to the gathering in Libya on Sunday he had seen signs the meeting could help end 4-1/2 years of violence in the devastated western region.

But he acknowledged wider rebel participation was needed, and diplomats said U.N. and African Union (AU) officials were expected to travel to Sudan in coming days to try to persuade key rebel leaders to abandon their boycott of the talks.

"We cannot lose momentum after we started serious and promising dialogue," Eliasson said, adding mediators wanted delegates to agree an agenda and identify pressing issues.

"This process must end with the outcome we are looking for. The all-inclusive process will continue and will not be adjourned. The word 'adjourn' is not relevant here."

Many rebel leaders are not attending the gathering, complaining at what they call government-inspired violence and a refusal by U.N. mediators to heed requests for a delay to allow them to form a united position and agree on a delegation.

"Nothing will be decided, including any endorsement of the ceasefire, until this goal is achieved -- more participation of the movements," rebel delegate Alhadi Agabeldour told Reuters, referring to a truce declared by Khartoum on Saturday.

"The most we could achieve from this meeting is to give more time for more participation of the other rebels."

The African Union-United Nations-mediated conference seeks to end a conflict that has sparked U.S. accusations -- dismissed by Sudan -- of genocide. Much of the killing has been blamed on a government-allied militia known as the Janjaweed.

Recently rebels have been blamed for attacks on African Union peacekeepers. In some cases, experts say, the rebel command structure has broken down to the point that the groups represent no constituency and are nothing more than bandits.

At the talks' opening the government declared an immediate unilateral truce, but the absence of key rebels cast doubt on whether it could be implemented. A 2004 ceasefire was rendered meaningless by repeated violations by all sides of the conflict.

"RIGHTS EQUAL PEACE"

Chief Sudanese government negotiator Nafie Ali Nafie said rebels boycotting the talks should be given more time to attend.

But he added: "Peace shall not be linked to those who do not want to attend. The mediators have to make it clear that those who do not want to attend must be sidelined."

The talks are the first attempt to gather Darfur rebels and the government around a negotiating table since 2006 when the AU mediated Darfur peace talks in Abuja, Nigeria.

Signed by only one rebel faction, the Abuja deal had little support among the 2 million Darfuris in displacement camps.

Rather than bring peace, it triggered fresh violence, as rebels split into more than a dozen factions, some preying on civilians, aid workers and AU troops sent to the region to quell the violence but unable to protect themselves.

Experts estimate 200,000 people have been killed and 2.5 million uprooted in violence since mostly non-Arabs took up arms in early 2003 accusing Khartoum of neglect. Khartoum puts the deaths at 9,000 and says the West exaggerates the conflict.

Rebel leader Bechir Tadjadine Niam told the conference peace could only come if Darfuris' rights were respected.

"Our rights equal peace. If we have no rights, there will be no peace," he said. "We tell the government we are ready to move to the middle ground. They have to do the same."

On the eve of the talks, two main rebel groups -- the Justice and Equality Movement (JEM) and the Sudan Liberation Army Unity faction -- said they would not attend.

That decision emerged after another rebel chief, Paris-based Abdel Wahed Mohamed el-Nur, founder of a third group, the Sudan Liberation Army (SLA), said he would not attend the talks.

Libya Sudan