Fighting between government forces and Tamil insurgents in Sri Lanka's north and east and a suicide bombing in the capital left dozens dead, including youths killed in what the rebels alleged was an air raid on a home for teenagers, officials said. The clashes along the frontiers dividing government and rebel territory in the north and east, and the blast in Colombo appeared to dash what little hope was left for a quick end to fighting that has steadily worsened over the past four weeks, undermining an already shaky cease-fire.The 2002 truce was intended to halt more than two decades of bloodshed between the government, dominated by Sri Lanka's 14 million Sinhalese, and the rebels, who have been fighting since 1983 for an independent homeland for the country's 3.2 million Tamils. While it remains officially in effect, months of shootings and bombings already had left it in tatters before the latest round of clashes. U.N. Secretary-General Kofi Annan was "increasingly alarmed" over the violence and called on both sides "to cease hostilities immediately and to return to the negotiating table," U.N. spokesman Stephane Dujarric said at U.N. headquarters in New York.