* May Iranian crude imports drop to 8-mth low of 1.02 mln T
* Iranian supplies down 18.6 pct in May from year ago
* But Jan-May crude imports from Iran up almost 60 pct y/y
* Total May crude imports remain flat y/y at 12.37 mln
By Jane Chung
SEOUL, June 15 (Reuters) - South Korea's Iranian crude oil imports dropped to their lowest in eight months in May, with Tehran struggling to maintain shipment volumes after exhausting stocks stored on tankers.
South Korea's Iranian crude intake fell 18.7 percent in May from a year ago to 1.02 million tonnes, or 242,058 barrels per day (bpd), customs data showed on Thursday. That was the lowest since last October when Seoul imported 902,987 tonnes.
Organization of the Petroleum Exporting Countries member Iran is exempt from an international drive to curb oil supply to boost prices, with the country pushing to regain market share lost during years of sanctions over its nuclear programme.
But it has already used up the crude it had in floating storage and is now fighting to boost output to support export volumes.
Iran's crude exports were set to fall to a 14-month low in May, a person with knowledge of Tehran's loading schedules said previously.
South Korea, one of Iran's major Asian customers, brought in 8.12 million tonnes of crude, or 394,324 bpd, over the January-May period. That was up nearly 60 percent from 5.08 million tonnes at the same time last year.
Meanwhile, South Korea's crude imports from Saudi Arabia rose in May even though the OPEC-led push to curb supply was last month extended until the end of next March. Saudi Arabia is the de facto leader of OPEC.
South Korea imported 4.23 million tonnes of crude oil, or 999,680 bpd, from the world's top crude exporter in May, up 18.6 percent from 3.56 million tonnes in April.
Overall, the world's fifth-biggest crude importer shipped in 12.37 million tonnes of oil, or 2.93 million bpd, the data showed. That was steady from 12.43 million tonnes a year ago.
In the first five months of 2017, South Korea imported 60.62 million tonnes of crude, or 2.94 million bpd, up 1.5 percent from 59.73 million tonnes over the same period in 2016.
Final data for May crude oil imports by state-run Korea National Oil Corp (KNOC) is due later this month. (Reporting by Jane Chung; Editing by Joseph Radford)