Clashes between government forces and fighters from an alliance of Darfur rebel groups have left 40 rebels dead, Sudan's army said Saturday, announcing a figure contested by the insurgents.

The fighting occurred on Friday in the Shangil Tobaya region, about 65 kilometres (40 miles) south of El-Fasher, historic capital of Darfur in western Sudan which has been gripped by civil war since 2003, the army said.

"The army attacked and defeated an alliance of the Justice and Equality Movement (JEM) and the Sudan Liberation Army of Minni Minnawi (SLA-Minnawi)," the official SUNA news agency quoted army spokesman Sawarmi Khaled Saad as saying.

"Forty rebels were killed and a number wounded," the spokesman said, adding that two soldiers were killed and 13 wounded.

The rebels in a statement however proclaimed victory in Friday's fighting and reported "two deaths and some injuries" in their ranks.

Since Thursday, fighters from JEM -- the most armed rebel group in Darfur -- and SLA-Minnawi have been fighting alongside each other against government troops, according to JEM military spokesman Ali al-Wafi.

According to Wafi, the Sudan Liberation Army of Abdelwahid Nur has also joined the newly formed Alliance of Resistance Forces but a top SLA-Abdelwahid official said talks were ongoing and nothing had been decided yet.

Such an alliance would bring together all the main Darfur rebel groups which have opposed the central government in Khartoum since 2003, accusing it of neglecting the development of the vast desert region.

Since the civil war broke out, some 300,000 people have been killed and another 2.7 million displaced, according to UN figures. Sudan says 10,000 people have died in the conflict.

The Khartoum government has been trying to secure for months a comprehensive peace agreement with all Darfur rebel groups to no avail.

Minnawi is the only rebel leader to have struck an agreement with Khartoum, but relations between them have soured and the rebels clashed with the army earlier this month.

According to UN officials, the clashes between Minnawi's supporters and troops have forced the displacement of more than 12,000 people in less than a week.

The latest reported fighting comes as south Sudan gears up for a vote on independence that could split Africa's largest nation in two.

The January 9 referendum is the key plank of the 2005 peace deal that put an end to two decades of civil war between north and south.