Two Arab tribes which have been battling off-and-on for months in Sudan\'s Darfur region have resumed clashes, leaving dozens dead, one of their leaders said on Friday. \"In total, 51 people were killed and 65 were injured,\" in fighting on Thursday, Ahmed Khiri, a Misseriya tribal leader, told AFP. A leader of the rival Salamat tribe confirmed that the fighting took place in Central Darfur state, but gave no casualty figures.