The United Nations has described Sudan's western Darfur region as one of the world's worst humanitarian crises.

• Around 2.5 million uprooted
• World's biggest relief operation
• 2006 peace deal failed to improve security

The conflict flared in 2003 when rebels in Darfur took up arms, accusing the government of neglecting the region.

Since then, civilians have come under attack from government troops, nomadic militia and rebel groups. The United Nations says as many as 300,000 people may have died. Khartoum puts the figure at 10,000.

The violence has also forced some 2.5 million people - mostly farmers and villagers from non-Arab groups - to flee their homes.

Khartoum denies accusations it has used Arab militias, known as Janjaweed, to crush the revolt.

But the International Criminal Court's prosecutor has charged Sudan's president with masterminding a campaign of genocide in Darfur.

The government and one rebel faction signed a peace deal in May 2006, but two others refused, and many new rebel groups have since formed.

Relief agencies say the violence makes it difficult to deliver aid in parts of Darfur.

A combined United Nations-African Union peacekeeping force began deploying in 2008, taking over from a small, overstretched AU force.

The deployment follows protracted wrangling between the international community and Khartoum.

The conflict has also spilled over Sudan's borders into Chad and Central African Republic.

(Unless otherwise stated, data is for July 2007, taken from the Darfur Humanitarian Profile series issued by the United Nations)

Total no. of people affected by conflict:	4.1 million
No. of internally displaced people in Darfur:	2.2 million
No. of Darfur refugees in Chad:	240,000 (UNHCR, December 2006)
Residential population affected by conflict:	1.78 million (U.N. report, Jan 2007)
No. of people receiving food aid:	2.3 million
Percentage of affected population accessible according to U.N. security standards:	73 percent
No. of humanitarians on the ground (national and international):	12,100
No. of humanitarian agencies supporting Darfur population:	75 NGOs (including Red Cross/Red Crescent); 14 U.N. agencies
Malnutrition (acute):	13.1 percent (2006 - up from 11.9 percent in 2005) (U.N. report, Jan 2007)
Mortality:	0.36 per 10,000 people per day (2006) (U.N. report, Jan 2007)