Oct 27 (Reuters) - The Sudanese government and Darfur rebels were to begin peace talks in Libya on Saturday but the absence of key rebel leaders put in doubt any agreement to end 4-1/2 years of violence.

Here are some facts about the conflict in the Darfur region.

* THE CONFLICT:

-- Rebels in Sudan's western Darfur region took up arms against the government in February 2003, saying Khartoum discriminated against non-Arab farmers and neglected the region.

-- Khartoum mobilized proxy Arab militia to help quell the revolt. Some militiamen, known locally as Janjaweed, pillaged and burned villages and killed civilians. The government has called the Janjaweed outlaws and denied supporting them.

-- Experts have estimated that at least 200,000 people have died and 2.5 million driven from their homes in the region since early 2003, some crossing the border into Chad, exacerbating a refugee crisis there. Sudan says 9,000 people have died.

-- The United Nations calls Darfur one of the world's worst humanitarian crises. The United States says the violence in Darfur amounts to genocide.

-- Rebels have been blamed for recent deadly attacks on African Union peacekeepers and aid workers. Ten AU troops were killed last month. However 45 people also died in an attack on the town of Muhajiriya in South Darfur, blamed on the government. Sudan's army later denied the attack on the town held by the Sudan Liberation Army (SLA), the only rebel faction to sign a peace deal.

-- Justice and Equality Movement rebels said they attacked the Defra oil field in Kordofan, which neighbours Darfur, on Oct. 23, killing 20 soldiers and taking five foreign hostages. They say they will assault other oil facilities until Khartoum meets conditions, including full representation in the national government and compensation for Darfuris.

* CEASEFIRE AND TALKS:

-- A ceasefire was agreed in Darfur in April 2004. The African Union sent 7,000 peacekeepers with a mandate to monitor the peace and protect those displaced in the camps. Since then, the ceasefire has been violated repeatedly.

-- A peace deal in May 2006 was signed by only one of three rebel negotiating factions. It was almost immediately rejected by many in Darfur who said it did not go far enough to ensure their security. Rebels have since splintered into a dozen factions, deepening the crisis.

-- United Nations and African Union diplomats called for new talks between Sudan's government and rebel groups in Libya, beginning on Oct. 27, but analysts say a lack of support from prominent rebels and a government weakened by a teetering southern Sudan peace deal, which had been considered a possible model for a Darfur agreement, undermined chances of success.

* PEACEKEEPING FORCE FOR DARFUR:

-- The U.N. Security Council approved a resolution on July 31 for a new operation known as UNAMID, the United Nations-African Union Mission in Darfur. The combined force is expected to start operations on Jan 1, 2008.

-- It authorized, for an initial period of 12 months, up to 19,555 military personnel and 6,432 international police. UNAMID will absorb the 7,000 African Union troops currently in Darfur. It is expected to cost more than $2 billion in the first year.

-- The mission will operate under a "Chapter 7" mandate on the use of force. This allows it to use force to protect itself and to ensure freedom of movement for its personnel and aid workers. Force could also be used to protect civilians.

-- The civilian head of the operation is Rodolphe Adada, former foreign minister of the Congo Republic. The force commander is Gen. Martin Agwai of Nigeria.

AlertNet news is provided by