* May U.S. crude imports drop 33.2% from year earlier
* Crude imports from Saudi up 15.5% from year earlier
* S.Korea has not imported Iranian crude since May 2019
* Total crude imports in May at 10.57 mln T, down 6.2% y/y
* Jan-May crude imports at 56.91 mln T, down 7.0% on-year (Recasts, adds details)
By Jane Chung
SEOUL, June 15 (Reuters) - South Korea's U.S. crude oil imports fell in May to their lowest since November 2018 as some refiners conducted maintenance amid a demand slowdown as fuel use was hit by the coronavirus pandemic, customs data showed on Monday.
In May, U.S. crude imports were 956,686 tonnes, or 226,210 barrels per day (bpd), according to the customs data. That was down 33.2% from 1.43 million tonnes a year earlier. The United States ranked as South Korea's No.3 crude supplier after Saudi Arabia and Kuwait last month.
South Korea, the world's fifth-largest crude importer, has sharply increased U.S. crude imports following the end in May 2019 of U.S. sanctions waivers that had allowed South Korea to buy Iranian crude oil. South Korea since then has not imported Iranian crude oil - mainly its condensate, an ultra-light form of crude oil - and has replaced it with U.S. light crudes.
South Korea's crude imports from Saudi Arabia, its top crude supplier, were 3.92 million tonnes in May, or 926,078 bpd, up 15.5% from 3.39 million tonnes a year earlier, the data showed.
Overall, South Korea's May crude imports totalled 10.57 million tonnes of crude oil, or 2.50 million bpd, down 6.2% from 11.27 million tonnes in the same month last year.
Two South Korean refiners, SK Energy and Hyundai Oilbank, conducted maintenance over April and May that cut into the country's need for imported crude oil.
In the first five months of the year, South Korea imported 56.91 million tonnes of crude oil, or 2.74 million bpd, down 7.0% from 61.17 million tonnes in the same period of 2019.
The country's final crude oil imports data from state-run Korea National Oil Corp (KNOC) is due later this month.
Reporting By Jane Chung; Editing by Tom Hogue