U.N. aid agencies say they have no access to an estimated 50,000 people trapped in a conflict zone in northern Sri Lanka. (..) The World Food Program is providing food assistance to more than 90,000 people in temporary transit centers in Vavunya and Jaffna districts. (..) WFP Spokeswoman, Emilia Casella, says a total of 150 metric tons of this food aid has gone into the conflict zone. "However, this is really only enough to feed about 60,000 people for five days," Casella said. "And, given that we do not even know exactly how many people are trapped in the conflict zone, our concern is that the food being sent in is not enough."