A drone attack early Friday sparked a fire at a Riyadh oil refinery, the Saudi energy ministry said, in an assault claimed by Yemen's Huthi rebels. "The Riyadh oil refinery was attacked by drones, resulting in a fire that has been brought under control," the ministry said in a statement, adding that no casualties were reported and oil supplies were not disrupted. The rebels claimed to have targeted energy giant Saudi Aramco in Riyadh on Friday with six drones. bur-sy-ac/lg