NEW : Fears voiced by U.N. for children trapped in the escalating fighting . Upsurge in hostilities follows cessation for Hindu New Year . UNICEF humanitarian chief : Large number of people crowded in very small area . Tamil Tigers , Putumattalan government locked in conflict lasting Sunday .
NEW : Fears voiced by UNICEF for children trapped in the escalating fighting . Upsurge in hostilities follows cessation for New Year . U.N. humanitarian chief : Large number of people crowded in very small area . Tamil Tigers , Sri Lanka government locked in conflict lasting nearly 25 years .