South Korea's crude oil imports from Iran increased 10.5% in June from a year earlier.
Seoul imported 281,338bpd of crude oil from Iran in June, compared with 254,900 bpd a year ago, customs data showed on Saturday.
In the first half of the year, South Korea's intake of Iranian oil jumped 51.5% to 375,597 bpd, over the same period a year ago.
South Korea is one of the main Asian customers for Iranian crude, including an ultra-light oil known as condensate.