GENEVA: The United Nations said on Friday that $1.6 billion was now needed to face a "looming catastrophe" in Yemen where a Saudi-led coalition has been launching air strikes against Houthi fighters in a campaign to restore the government in exile. "Over 21 million people or 80 percent of the population are now estimated to be in need of some form of humanitarian aid and or protection," UN spokesman Jens Laerke told a news briefing. Stephen O'Brien, UN Under-Secretary-General for Humanitarian Affairs, launched the revised funding appeal, telling donors that a "looming catastrophe" was in the making across Yemen with families struggling to find food, he said.