French President Nicolas Sarkozy said on Friday everything had to be done to prevent a "terrorist or Islamic state” emerging in northern Mali after rebels seized vast tracts of the desert north.A March 22 coup emboldened Tuareg nomads to seize the northern half of Mali and declare an independent state there. Al Qaeda-linked Islamist fighters are among the rebels, and analysts fear the desert zone could become a haven for al Qaeda agents and a destabilising "rogue state” in West Africa.Sarkozy said he supported some form of autonomy for the Tuaregs in the former French colony."We have to work with the Tuaregs to see how they can have a minimum of autonomy and we must do everything to prevent the establishment of a terrorist or Islamic state in the heart of the Sahel,” Sarkozy told i Tele television.France is Mali’s fourth-largest aid donor - a vital source of income in one of the world’s poorest countries. France also trains and equips government forces.Mali’s former parliament speaker Dioncounda Traore took over as interim president on Thursday as part of a deal to restore civilian rule following the coup.He called on the separatists to pull back from the northern towns they occupied, which include the desert trading post and seat of Islamic learning Timbuktu and the garrison town of Gao.