SEOUL (Reuters) – South Korea halted all imports of Iranian oil in May, customs data showed on Saturday, as waivers on U.S. sanctions against Iran ended at the start of last month.

The world’s fifth-largest crude oil importer was among countries granted six-month waivers by the United States in November last year, and resumed Iranian oil imports from January this year after a four-month hiatus.

The country’s imports of Iranian crude for the January-May period, were 3.87 million tonnes, or 187,179 bpd, compared to 5.45 million tonnes over the same period last year, the customs data showed.

South Korean oil buyers mainly imported condensate, an ultra-light oil, from Iran.

SK Innovation, the owner of South Korea’s top refiner SK Energy and petrochemical maker SK Incheon Petrochem, said in late May that it has been replacing Iranian condensate with crude oil from other sources, including Qatar and Russia.

South Korea’s total May crude oil imports fell 11.1% to 11.27 million tonnes, or 2.65 million bpd.

Oil shipments from Saudi Arabia, the country’s top crude oil supplier, rose 5.1% to 3.39 million tonnes, or 798,695 bpd, from a year earlier, the data showed.

Qatari crude oil imports rose 10.1% year-on-year to 660,752 tonnes, or 155,596 bpd.

South Korea also imported 1.43 million tonnes of crude oil, or 337,014 bpd, in May from the United States, more than tripled from 405,158 tonnes a year earlier, according to the data.

The country’s crude oil imports from January to May edged up 0.3 % to 61.17 million tonnes year-on-year.

State-run Korea National Oil Corp (KNOC) will release the country’s final crude oil imports data later this month.