South Korea's prices of imported farm goods posted a negative growth for three straight months in May due to a fall in agricultural product prices that offset a rise in prices for livestock and fishery products, customs data showed Tuesday.

The import price index for agricultural, livestock and fishery products reached 117.2 points in May, down 3.8 percent from a year earlier, according to the Korea Customs Service (KCS). From a month before, the index rose 1.9 percent.

The index logged the on-year fall for three months in a row last month after marking its first on-year drop in 17 months in March.

Prices for imported agricultural products plunged 6.5 percent in May from a year before. Vegetable prices showed an overall downward trend last month, while prices of cereals, fruits and nuts mostly showed stable trend.

Meanwhile, prices of imported livestock products gained 3.5 percent on-year in May. Chicken meat led the May gain with an on- year surge of 53.2 percent. Pork prices increased 11.6 percent over the cited period, with beef prices inching up 0.1 percent.

Prices for fishery products advanced 2.5 percent in May from the previous year. Prices of snow crab, scallop and pollack jumped 59.5 percent, 30.7 percent and 4.5 percent respectively, but those of hairtail and small octopus declined 8.7 percent and 8.9 percent each.