South Korea's terms of trade improved for an eighth straight month in April as lower oil prices worked to drag down import prices more sharply compared with the fall in export prices, data showed Tuesday.

The country's net terms-of-trade index for goods climbed 11.7 percent on-year to 99.56 last month, slightly picking up from 11.3 percent on-year growth in March, according to the preliminary data by the Bank of Korea.

The index gauges the quantity of imports that can be purchased through the sale of a single unit of exports. The base year, set in 2013, is 2010 with a benchmark of 100.

The rise in the reading came as import prices dropped 19 percent, compared with a 9.6 percent fall in export prices, the central bank explained.

The data, meanwhile, showed that the country's income terms-of-trade index, which measures how much can be imported with the total export value, jumped 12.9 percent on-year, slowing from a 16.1 percent surge in March. (Yonhap)