An explosion on a natural gas pipeline outside an Iranian border city has halted the flow of gas to Turkey, Iranian authorities said Friday. The governor of Maku, a town in western Iran near the Turkish border, Safar Aseri, said the fire broke out at 11:30 p.m. Thursday (2000GMT) and was extinquished an hour later, state-run radio reported Friday. Aseri was quoted as saying the cause of the explosion was under investigation. But officials at the Iranian Embassy in Ankara said they believed the explosion was an act of sabotage by separatist Kurdish rebels who are active on both sides of the Iran-Turkey border.