The world's fifth-biggest crude oil importer has increased imports of Iranian crude, mainly condensate, or an ultra-light oil, since sanctions were lifted in 2016, reported Reuters.
However, imports have fallen this year, partly reflecting a cut in supplies to South Korea by National Iranian Oil Company due to lower production and the start of a new splitter, sources have said.
South Korean refiner Hyundai Oilbank made its first purchase of Norwegian condensate, while SK Incheon Petrochem said it would continue to buy light crude including from Russia and Kazakhstan.
In the first four months of this year, South Korea's intake of Iranian oil dropped 34 percent to 4.69 million tons, or 286,308 bpd, versus about 7.1 million tons over the same period a year ago, the data showed.
In total, South Korea's April crude oil imports were 11.59 million tons, or 2.83 mbd, up 2.5 percent from 11.30 million tons from 2017, according to the data.
April crude imports from Saudi Arabia, South Korea's top crude oil supplier, fell 6.9 percent to 3.32 million tons, or 810,564 bpd, from last year.
Meanwhile, South Korea imported 1.01 million tons from Russia in April, or 33,689 bpd, up 132.4 percent from 434,974 tons last year, according to the data.
For the January-April period of this year, South Korean brought in 48.29 million tons of crude, or 2.95 mbd, up 0.2 percent from 48.18 million tons in the same period in 2017.
Final data for the country's April crude imports data will be released by state-run Korea National Oil Corp. (KNOC) later this month.