The United Nations said on Friday that five of its Afghan workers had gone missing and it was trying to determine what had happened to them, according to Reuters. Dan McNorton, spokesman for the U.N. mission in Kabul, said the five worked for the U.N. Office of Project Services. He gave no further details as to how they had gone missing. U.N. staff have been targetted by kidnappers in Afghanistan in the past. All foreign staff were accounted for. "The U.N. is currently working with the Afghan authorities to ascertain their current whereabouts and the exact circumstances of their situation," he said. The United Nations reduced its international staff in Afghanistan and the number of locations where they are based last year after five foreign staff members were killed by gunmen in an attack on a guesthouse in October in Kabul.