U.S. import prices surged in April, with the cost of fuels posting the largest increase in four years, another indication that the U.S.-backed war with Iran was boosting inflation. Import prices increased 1.9% last month after an upwardly revised 0.9% rise in March, the Labor Department's Bureau of Labor Statistics said on Thursday. Economists polled by Reuters had forecast import prices, which exclude tariffs, would increase 1.0% after a previously reported 0.8% advance in March.