British ex-prime minister Gordon Brown launched an appeal Tuesday in his role as UN education envoy to raise $100 million in aid for Syrian students who have taken refuge in Leba**n. "Over the next 100 days we must have allocations of around $100 million provided so that the minister (of education in Leba**n) can increase the enrolment in his schools," Brown told a news conference in Beirut. Leba**n has an official population of four million, but it is estimated to host 1.2 million refugees who fled the conflict in neighbouring Syria over the past four years.