The acute problems of the world's poorest countries form the agenda of a U.N.-backed conference this week in Turkey , which has sought to balance its traditional Western alliances with growing ties to Africa, the Middle East and other developing regions. The conference of "least-developed countries" lists 48 members, including Afghanistan, where a U.S.-led coalition is fighting Taliban insurgents, and Yemen, where at least 140 protesters have died during months of demonstrations aimed at ousting the president. Up to 10,000 delegates are expected to attend the five-day forum, which starts Monday. Among them are U.N. Secretary-General Ban Ki-moon, EU Commission President Jose Manuel Barroso, Afghan President Hamid Karzai and Iranian President Mahmoud Ahmadinejad, whose oil-rich country is not in the list of poorest countries.