South Korea's terms of trade worsened for the 11th consecutive month on an expensive crude oil, central bank data showed Friday.

The net terms-of-trade index for goods stood at 92.78 in October, down 8.8 percent from a year earlier, according to the Bank of Korea (BOK).

The index refers to the amount of imports that can be bought with the unit-export proceeds.

The figure kept falling since December last year amid the higher global crude oil price, marking the lowest in almost four years.

Dubai crude in September, which was reflected in the October trade terms, averaged 77.23 U.S. dollars per barrel, up 43.9 percent from a year earlier.

Export volume jumped 25.8 percent in October from a year earlier, posting the fastest increase since January 2011.

In terms of value, the outbound shipment advanced 27.9 percent last month on higher export price for oil product.