While Sudan's government at Khartoum admits mobilising "self-defence militias" following rebel attacks, it denies any links to a group called the Janjaweed, the primary agressors against the Darfuris, who are accused of trying to "cleanse" black Africans from large swathes of territory.

For their part, Sudan's government and the pro-government Arab militias are accused of war crimes against the region's black African population, although the UN has stopped short of calling it genocide. 

Refugees from Darfur say that following air raids by government aircraft, the Janjaweed ride into villages on horses and camels, slaughtering the men, abusing women and stealing what they can.  Many women report being abducted by the Janjaweed and held as slaved for as long as a week.

Sudan's government denies being in control of the Janjaweed and the Sudanese President, Omar al-Bashir, has called them "thieves and gangsters".  The government has promised to disarm the Janjaweed, but so far there is little evidence this has happened.

As a result of the conflict, millions of Darfuris have been forced to flee their destroyed villages, many heading for camps near Darfur's main towns. But there is not enough food, water or medicine.  And the Janjaweed patrol outside the camps where Darfurians say men are killed and the women grossly abused if they venture too far in search of firewood or water.

Some 200,000 refugees have sought safety in neighboring Chad, but many of them remain camped along a 600km stretch of the border that is vulnerable to regular attacks by raiders.  The refugees are also threatened by the diplomatic fallout between Chad and Sudan as the neighbours accuse one another of supporting each other's rebel groups.

Many aid agencies are working in Darfur but they are unable to get access to vast areas because of the fighting.

With much of Darfur inaccessible to aid workers and researchers, calculating how many deaths there have been in the past three years is impossible.  What researchers have done is to estimate the deaths based on surveys in areas they can reach.  The latest research published in September 2006 in the journal Science puts the numbers of deaths above and beyond those that would normally die in this inhospitable area at "no fewer than 200,000".

About 7,000 African Union troops have slowly been deployed in Darfur on a very limited mandate.  Experts say the soldiers are too few and the African Union says it does not have the money to fund the operation for much longer.  So far, the government of Sudan has resisted strong western diplomatic pressure for the UN to take control of the peacekeeping mission. The latest plan calls for 17,000 troops and 3,000 UN policemen but at present there is deadlock.

Outgoing UN chief Kofi Annan has said Sudan has agreed in principle to allow a joint peacekeeping force into Darfur.

A dossier of evidence compiled by a UN commission has been passed to the ICC in The Hague, along with the names of top war crimes suspects.

Click here for the full BBC report from 16 November 2006.