Sri Lanka's ethnic Tamil leaders on Sunday asked the top human rights official of the United Nations to help determine the fate of more than 4,000 civilians reported missing in the country's long civil war amid the government's assertion that most of them are probably dead. UN High Commissioner for Human Rights, Zeid Raad al-Hussein, met the chief minister of Sri Lanka's Northern Province, the arena of the civil war, which ended in 2009. Zeid arrived in Sri Lanka on Saturday on a four-day visit aimed at reviewing the measures taken by the island nation to investigate alleged atrocities committed during the long civil war that left tens of thousands dead. Both the Sri Lankan government and the defeated Tamil Tiger rebels are accused of serious human rights violations. According to U.N. estimates, up to 100,000 people were killed in the 26-year war, but many more are feared to have died, including up to 40,000 civilians in the final months of the fighting. The U.N. Human Rights Council last