South Korea's index of import prices rose for the sixth consecutive month in June on a weakening local currency, but the growth slowed due to a decline in crude oil prices. 

According to preliminary data from the Bank of Korea(BOK), the import price index gained one-point-three percent to reach 88-point-26 in June from a month earlier. It jumped ten-point-nine percent compared to the same period last year. 

The index has been on a steady rise since January due to the strengthening of the U.S. dollar against the won and a steady growth in oil prices. In particular, the index jumped two-point-seven percent in May, the largest gain in 18 months. 

However, the growth slowed in June as crude oil prices fell slightly. Dubai crude, South Korea's benchmark, inched down one-point-one percent on-month in May to an average of 73-point-61 dollars per barrel. 

A BOK official said that the gain of import prices could widen as oil prices are rising more steeply in July than June, and the greenback is further strengthening against the won in this month.