A veteran diplomat who has served as Mideast envoy under Democratic and Republican presidents will be a special adviser to US Secretary of State Hillary Clinton on the Persian Gulf region, officials said Monday. The State Department announced that Dennis Ross will be asked to provide Clinton with assessments, strategic advice and perspective. Ross worked on the Middle East peace process for the administrations of former US Presidents George H.W. Bush and Bill Clinton. Former Sen. George Mitchell is the administration's special envoy for Mideast peace, and Richard Holbrooke is special coordinator for Afghanistan and Pakistan.