The United Nations has increased the latest death toll in Asia’s tsunami disaster to more than 150,000, warning it could still soar as relief workers were confronted by huge devastated areas without roads, bridges and airstrips. Helicopters and elephants became the most useful tools for relief teams trying to reach remote areas to find and feed survivors and shift the rubble of razed towns. Aid workers struggled to help thousands huddled in makeshift camps on Indonesia’s northern Sumatra island, where the tsunami claimed two thirds of its victims, and the U.N. said it was concentrating efforts on the area due to the threat of disease. In Sri Lanka, the second worst-hit nation with more than 30,000 dead and 850,000 homeless, there was little sign of an organized government relief effort, but food distribution looked to be smoother. Meanwhile, a women’s collective in Sri Lanka said rapists were preying on survivors at refuge centers. The U.N International Children’s Emergency Fund (UNICEF) estimates about 50,000 children died across South Asia — a third of the toll. Tens of thousands more have been orphaned. In other developments, President Bush named his father and former President Bill Clinton as the joint coordinators of a campaign to encourage Americans to donate to exisiting charities. Meanwhile, U.S. Secretary of State General Colin Powell and Florida Governor Jeb Bush arrived in Phuket, Thailand on Tuesday to begin their tour of the tsunami-hit region. After meeting the Thai Prime Minister and Foreign Minister upon their arrival in Bangkok, Powell and Bush flew to Phuket where they held a joint news conference.