South Korea's energy import shrank in the second quarter as cheaper oil reduced costs of energy imports, customs data showed on Thursday.

Energy imports were valued at 22.46 billion U.S. dollars during the April-June period, down 34.9 percent from the same period of last year, according to the Korea Customs Service (KCS).

The ratio of energy imports to the total imports during the second quarter fell to 20.3 percent from 26.3 percent a year earlier.

The lower cost of energy imports came as global oil prices declined in the quarter. In terms of volume, imports of energy like crude oil, natural gas and coal increased 7.6 percent on a yearly basis.

Crude oil imports jumped 17.3 percent in the second quarter from a year earlier, but the value of imported crude slumped 34.7 percent to 15.4 billion dollars.

Coal import volume rose 3.5 percent in the quarter, but the value of coal import plunged 16 percent. The natural gas import volume fell 8.1 percent, and the value of natural gas imports tumbled at a faster pace of 43.3 percent.