* April Iran oil imports at 552,884 T, double m/m, up 9 pct y/y
* Jan-April Iran oil imports at 135,982 bpd, down 8 pct y/y
* Jan-April daily Iran import avg just above 134,000 bpd of 2013
* Total crude imports in April at 9.5 mln T, up 2 pct y/y
By Meeyoung Cho
SEOUL, May 15 South Korea's crude imports from Iran doubled in April from March, when the shipments dropped due to refinery maintenance, but intake of the oil over the first four months remained near last year's average, customs data showed on Thursday.
South Korea imported 552,884 tonnes of Iranian crude last month, or 135,088 barrels per day (bpd), compared with 274,808 tonnes a month ago and 507,821 tonnes a year ago, according to the preliminary customs data.
South Korea took 2.2 million tonnes, or 135,982 bpd, in the first four months of this year from the Islamic republic, down 8 percent from the same period in 2013 and slightly more than the average 134,000 bpd for all of last year.
South Korea and other Asian buyers are supposed to hold their crude imports from the OPEC member at end-2013 levels, under the terms of the Geneva accord between Iran and six major powers that took effect in January and eased some sanctions on Tehran in exchange for curbs to its nuclear programme.
In South Korea, only SK Energy and Hyundai Oilbank of four refiners buy Iranian oil. The country's Iran oil imports often swing widely month to month as one of the two usually buys the crude only every other month.
SK Energy, South Korea's largest refiner, shut its 260,000-bpd No.5 crude distillation unit (CDU) and its 57,000-bpd No.1 gasoline-making unit in the second quarter for maintenance after it closed a vacuum residue desulfurizer from March to April.
Hyundai Oilbank also shut its No.1 110,000-bpd CDU in April for maintenance.
A tanker loading schedule seen by Reuters in April suggests that South Korea will be importing very little oil from Iran in May due to the maintenance closures.
South Korea, Asia's fourth-largest economy, imported a total of 9.5 million tonnes of crude last month, or 2.3 million bpd, compared with 9.3 million tonnes in April last year, the customs data showed.
Final data for April crude oil imports will be released by state-run Korea National Oil Corp later this month.
India cut its Iranian crude imports by 42 percent in April from March, tanker arrival data obtained from trade sources showed on Wednesday, in a sign other Asian buyers are reining in an early-year buying spree that took Tehran's exports well past levels allowed under the Geneva deal.
(Editing by Tom Hogue)