South Korea's trade terms worsened in the first quarter as import price growth outpaced export price rise, the central bank said Monday.

Net terms-of-trade index for goods, calculated by dividing per- unit export price index by per-unit import price index, stood at 80.6 in the first quarter of this year, down 5.6 percent from a year earlier, the Bank of Korea (BOK) said in a statement.

The aggravated trade terms came as the per-unit import price growth outpaced per-unit export price advance amid rising commodity prices, according to the BOK.

The per-unit import price index jumped 14.6 percent on-year for the first three months of this year due to higher raw material prices.

The per-unit export price index gained 8.2 percent in the first quarter from a year earlier as price rises in oil and steel products overshadowed price declines in semiconductors, the BOK said.