A major UN do**rs' conference that aims to raise billions of dollars for Syria opens Tuesday in Kuwait with experts warning of a "humanitarian catastrophe" unfolding in the war-torn country. The United Nations has launched an appeal to raise $8.4 billion (7.7 billion euros) this year, and hopes to receive major pledges at the one-day conference which will be attended by delegates from 78 nations. UN Secretary-General Ban Ki-Moon will chair the Third International Pledging Conference for Syria, which will be opened by Kuwait's Emir Sheikh Sabah al-Ahmad al-Sabah. "Failing to meet the required funds risks resulting in a horrifying and dangerous humanitarian catastrophe," Abdullah al-Maatuq, UN special envoy for humanitarian affairs, has said.