The United States says government-backed militias in Sudan may be violating a ceasefire in the western Darfur region.
The Sudanese government and rebels agreed last week to observe a 45-day ceasefire in Darfur beginning Monday to allow aid groups to provide much needed humanitarian relief.
However, State Department spokesman Richard Boucher says reports received by Washington indicate the government-backed Arab militias, who have been driving black Africans out of Darfur, appear to be continuing their attacks.
Mr. Boucher says it has reports of militia attacks in western and southern Darfur as well as aerial bombardments northwest of the Sudanese capital, Khartoum.
The assessment is at odds with government and rebel assurances that the ceasefire was being respected.
The year-old conflict in Darfur has displaced more than 600,000 people inside Sudan and forced about 100,000 others to flee to neighboring Chad.
Meanwhile, the United States has warned of possible U.S. sanctions against Sudan if a peace agreement is not reached soon between the Khartoum government and southern rebel group, Sudan People's Liberation Army. The two sides have been holding peace talks in Kenya aimed at ending two decades of civil war.
The latest snag reportedly centers on whether the capital Khartoum should remain under Islamic law after a peace agreement is signed.
The government wants the Khartoum to remain under Islamic law, but the rebels want the capital to be exempt from it.
Some information for this report provided by AFP and Reuters.