Tribal violence and not rebel activity is the major security threat to Sudan's Darfur region, the defence minister said on Tuesday.

Battles between Arab tribal militias have worsened this year in Darfur, leaving hundreds dead in the country's far-west region, where a decade-long rebellion also continues.

"The tribal clashes are the biggest challenge and threat to security in Darfur, more than rebel movements," Defence Minister Abdelrahim Mohammed Hussein said in a briefing to parliament.

He said tribal unrest has occurred in four of the region's five states.

Non-Arab rebels rose up 10 years ago in Darfur, seeking an end to what they called the domination of Sudan's power and wealth by Arab elites.

In response, government-backed Janjaweed militia shocked the world with atrocities against civilians.

Analysts say the cash-starved government can no longer control its former Arab tribal allies, whom it armed against the rebellion, and violent competition for resources has intensified.

The Hague-based International Criminal Court issued a warrant for Hussein's arrest in March last year on 13 counts of alleged crimes against humanity and war crimes in Darfur.