(Refiles to add dropped word to headline) LAUSANNE, Switzerland, March 30 (Reuters) - The death tollfrom an air strike at a refugee camp in **rthern Yemen on Mondayreached 45, with 65 were wounded, a spokesman for theInternational Organization for Migration told Reuters. A Saudi-led coalition is bombing Yemen for a fifth day totry to weaken the Iran-allied Houthi militia and military unitsfighting alongside them as they advance south towards the portcity of Aden, the last bastion of President Abd-Rabbu MansourHadi. (Reporting by Stephanie Nebehay and **ah Browning; editing byJohn Stonestreet)