UNITED NATIONS — The Sudanese government, which has been accused of backing violent groups in Darfur, is poised to emerge as a major victor from a U.N.-sponsored peace conference in Libya, scheduled to begin Saturday, diplomats say.

The event, once billed as the ultimate drive toward a negotiated peace in the five-year war in Sudan’s western region, which the Bush administration has characterized as genocide, now appears doomed to be a crashing failure. Some of the major Darfur players are not likely to attend, the organizers have said. The Sudanese government, therefore, is expected to present itself as seeking peace and its enemies in Darfur as bloodthirsty warlords.

The rebels in Darfur say they do not trust the government, which they say has reneged repeatedly on its promises. They have hesitated to sign any agreement with Khartoum before the deployment of a force of at least 20,000 U.N.-led troops in the region.

The government, in turn, has resisted the deployment of force, which would have a shared U.N.-African Union command. Contributions of troops and equipment have also been slow to materialize.

“This is a test for the Security Council and for the U.N.,” the Sudanese ambassador to the United Nations, Abdalmahmood Abdalhaleem Mohamad, said yesterday, referring to the upcoming talks in Sirte, Libya.

Colonel Muammar Gadhafi of Libya will host the conference, but representatives of the United Nations and the African Union are organizing it. If top leaders of the rebel groups in Darfur fail to show up, “they will expose themselves as they are: warlords not interested in peace,” Mr. Mohamad told the Sun. A high-level adviser to President al-Bashir of Sudan, Nafie Ali Nafie, will represent the Sudanese government. As the Sirte talks were drawing near, Darfuri rebel groups jockeyed for position, fighting the government and one another while government-backed militias, known as the Janjaweed, committed new atrocities. A two-year-old peace agreement between Khartoum and another oppressed group in southern Sudan appeared to be on the verge of collapsing, as southern representatives left their posts in Mr. Bashir’s coalition government. The development led to further chaos in Darfur.

“We started out with two rebel groups in Darfur. Now we have 14,” a frustrated senior Western diplomat who briefed reporters yesterday on condition of anonymity said.

While some rebel representatives are expected to attend the conference in Libya, the leaders with the largest following have already announced that they will not be there.

The U.N.-organized parley “is completely the wrong approach and will only prolong the suffering of our people,” the leader of the Sudan Liberation Movement, Abdel Wahid Nur, told the Los Angeles Times. Talks should take place “only after promised U.N. peacekeepers are deployed in Darfur and security is restored,” he said.

The U.N. representative in Sudan, Jan Eliasson of Sweden, emphasized yesterday that Darfur’s “civil society groups” will be represented in the talks if the government allows them to travel. But he also acknowledged “the need to lower expectations,” as the main factions are unlikely to attend.

Long-term issues such as power sharing between the sides and division of resources and land will have to wait for future negotiations, Mr. Eliasson said.

The Western diplomat who briefed reporters yesterday said future negotiations might produce better results. Such talks might take place outside Libya, which he said has ties to many of the warring factions and “was not our first choice” to host the conference.