GENEVA (Reuters) - The International Organization for Migration said it had a report of 40-50 migrants missing at sea off Libya on Friday, but there were no immediate details or confirmation. IOM spokesman Joel Millman said that there had been 2,701 deaths so far this year and more than 364,000 people had arrived in Greece, Italy and Spain after crossing the Mediterranean Sea. (Reporting by Tom Miles; Editing by Alison Williams)