South Korea's import prices retreated last month from a month earlier due to a fall in prices for crude oil and petroleum products, the central bank said Friday.

In local currency terms, import prices declined 1.9 percent in May from a month before, down from a 1 percent on-month fall tallied in the previous month, according to the Bank of Korea (BOK) . From a year earlier, the prices advanced 2.1 percent.

The May figure posted the two straight month of on-month decline due to falling oil prices. Dubai crude, South Korea's benchmark, averaged 107.3 U.S. dollars a barrel in May, down 8.5 percent from the previous month.

Import prices for raw materials decreased 3.9 percent on-month in May, down from a 2.3 percent on-month decline a month before. Prices for mining products imported from overseas dropped 4.2 percent, with agricultural product prices falling 1.8 percent.

Intermediate goods prices were down 0.7 percent in May from the previous month after posting a 0.2 percent fall in April. Petroleum product prices tumbled 11 percent amid lower oil prices, and prices for primary nonferrous metal products dipped 1.6 percent.

Prices for capital goods gained 1.6 percent on-month in May, but consumer goods prices declined 0.9 percent over the same period.

In contract currency terms, import prices fell 3.6 percent on- month in May. The South Korean currency depreciated 1.6 percent against the greenback last month.