The United Nations investigated more than 300 members of UN peacekeeping missions for alleged sexual exploitation and abuse during the past three years and more than half were fired or sent home, a senior UN official said. UN Assistant Secretary-General for Peacekeeping Jane Holl Lute said Friday the UN has done more in the last two years than ever before to try to combat sex abuse in its 16 peacekeeping missions with over 92,000 personnel, "but we're not satisfied with where we are." With nearly 200,000 people from over 100 countries rotating through the peacekeeping missions every year, some people "are going to behave badly," she told a news conference. "What's different now is ... our determination to stay with this problem ... and constantly improve our ability to deal with it." While allegations of abuse have dogged peacekeeping missions since their inception over 50 years ago, the issue was thrust into the spotlight after the United Nations found in early 2005 that peacekeepers in Congo had sex with Congolese women and girls, usually in exchange for food or small sums of money.