South Korea's import price index hit a near four-year high last month due mainly to a weaker local currency. 

According to preliminary data from the Bank of Korea on Tuesday, the import price index posted 89-point-91 in July, up one-point-seven percent from a month earlier. 

It is the highest monthly figure since November 2014, when the index touched 91-point-23. The index has been rising for seven consecutive months since January. 

The central bank said that in spite of a point-seven percent drop in crude oil prices, the weakening Korean won pushed up import prices last month. The local currency lost two-point-seven percent against the U.S. dollar in July alone to average one-thousand-122-point-80 won. 

Meanwhile, the country's export price index in terms of local currency posted 87-point-56 in July, up two-point-three percent on-month. The index also marked its highest level since November 2014.