Fresh fighting has broken out in Darfur just hours after Sudanese President Omar al-Bashir signed a peace deal with rebels, dpa quoted aid workers as reporting. Al-Bashir and Justice and Equality Movement (JEM) leader Khalil Ibrahim inked the deal in Doha on Tuesday, raising hopes of a definitive peace in the restive Sudanese province. However, French aid group Medecins du Monde said it had been forced to suspend its operations in the region of Feina after heavy fighting on Wednesday. "Deribat, a town of 50,000 inhabitants, was attacked on Wednesday, provoking the mass flight of the population and bringing to 100,000 the number of displaced in the area," Medecins du Monde said in a statement on its website, without saying who was conducting the fighting. Reports said that the government attacked positions of the Sudan Liberation Army (SLA), which has not signed up to the peace deal. The government in Khartoum has signed several previous ceasefire agreements that have quickly fallen apart, but many analysts see more hope this time around. In a significant move, Khartoum on Wednesday released 57 JEM rebels, held after a 2008 attack launched an Omurdman, which lies across the River Nile from the capital Khartoum.