More than 10,000 civilians have fled Sri Lanka's northern war zone over the last two days, an official said Sunday as government forces appear poised to crush the separatist Tamil Tigers. The military's relentless offensive in recent months has almost routed the rebels, virtually ending their 25-year war for a separate Tamil nation in the Sinhalese-majority country. The United Nations and aid agencies have expressed concern for the estimated 250,000 civilians trapped in the shrinking sliver of land still controlled by the Tigers. Sri Lanka barred nearly all aid groups from the war zone last year. It does not allow journalists in either, making independent verification of the situation impossible. Some 70,000 people have died in Sri Lanka's civil war, which began in 1983 after years of marginalization of the Tamil minority by governments dominated by the Sinhalese majority.