GAO, Mali (Reuters) - One of al Qaeda's most feared commanders in Africa has been killed by French air strikes in north Mali, sources close to Islamist militants and tribal elders said on Friday, but France said it could not confirm this. The local sources said Abdelhamid Abou Zeid, blamed for kidnapping at least 20 Western hostages in the Sahara desert in recent years, was among 40 militants killed four days ago in the foothills of the Adrar des Ifoghas mountains. About 1,200 French troops and 800 Chadian soldiers are hunting down pockets of al Qaeda-linked insurgents in the border...