South Korea's producer prices made a downturn in May for the first time in almost seven years on the strengthening local currency, the central bank said Tuesday. According to the Bank of Korea (BOK), the producer price index, an indicator to help forecast future consumer inflation, logged an on-year 1.3 percent decline in May, while it earned 1.5 percent annually the previous month. It was the first drop in producer prices since August 2002 when the figure marked a contraction of 0.1 percent, the BOK said. The fall in May was contributed by the stronger local currency, which pushed down prices of imported materials and goods, a BOK official said. 'Stagnant local demand stemming from an economic slowdown was also responsible,' the official added. 