The United States on Thursday urged an immediate ceasefire in Sri Lanka to save thousands of trapped civilians, saying the Colombo government had a chance to finally end three decades of war. “We call upon the government and military of Sri Lanka and the Tamil Tigers to immediately stop hostilities until the more than 140,000 civilians in the conflict are safely out,” State Department spokesman Robert Wood said. “The Sri Lankan government, as legitimate sovereign power, has before it an opportunity to put an end to this lengthy conflict,” Wood told reporters. But he said a lasting peace would only come “through a political solution that addresses the legitimate aspirations of all Sri Lankan communities.” On the same day, Sri Lanka said it had made fresh advances into an area still held by the Tiger rebels, who launched a campaign in 1972 to create a separate homeland on the island for the Tamil minority. “Further killing, particularly killing of civilians, will not end the conflict and will stain any eventual peace,” Wood said. He called on Sri Lanka to use diplomacy “to permit a peaceful outcome of this conflict.” “We call on the Sri Lankan government to put forward a proposal now to engage Tamils who do not espouse violence or terrorism and to develop power-sharing arrangements so that lasting peace and reconciliation can be achieved,” he said. The United States considers the Tamil Tigers, known for their trademark suicide bombings, to be a terrorist organization.