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* Imports 686,849 T of Iranian crude in June versus 1.15 million T year
* Iran's H1 oil imports decreased 33.9 pct in the year to 6.13 million tons  * S.Korea buyers reduce Iran's oil purchases before US sanctions
* June's total crude imports rose 13.2% to 13.14 million tons per year
By Jane Chung
SEOUL, July 15 (Reuters) – Imports from South Korea Iranian oil fell 40.3 percent in June from the same month a year ago to its lowest level since January 2015, because The country's buyers cut back their purchases before the re-imposition of US sanctions against Iran.
South Korea, one of Iran's main oil customers in Asia, imported 686,849 tons of Iranian crude in June, or 167,820 barrels per day (bpd), compared to 1.15 million tons in June 2017, according to data from the customs office on Sunday. That was 9.5 percent since May.
In the first half of this year, South Korea's Iranian crude consumption fell by 33.9 percent compared to the same period last year to 6.13 million tons, or 248,367 bpd, according to data.
The fall comes after the government of US President Donald Trump said he would withdraw from an international nuclear agreement with Iran and would renew harsh economic sanctions on Tehran.
Seoul has been in talks to obtain an exemption from the United States in an attempt to avoid any adverse impact by stopping imports of Iranian oil. In August, people familiar with the issue said, South Korea's oil imports could be zero for the first time in six years.
South Korea buys mainly an ultra-light form of crude oil, known as condensate, from Iran, and its data does not give a product breakdown.
In 2012, South Korea managed to obtain an exemption in the previous round of sanctions by importing limited quantities of Iranian oil during that time. Those sanctions were lifted in 2016.
In total, South Korea's crude oil imports in June were 13.14 million tons, or 3.21 million barrels per day, up 13.2 percent from the 11.61 million tons in the same month of last year.
From Saudi Arabia, South Korea's main crude supplier, crude oil imports in June rose 26.1 percent to 4.38 million tons, or 1.07 million bpd, from last year . Shipments from Mexico showed an almost five-fold increase to 568,377 tons.
South Korea's crude oil imports in the first six months of this year were 74.11 million tons, or 3 million bpd, an increase of 2.7 percent from 72.17 million tons during the same period in 2017, according to the data.
Figures for the country's crude imports at the end of June will be released by Korea National Oil Corp (KNOC) later this month. (Reporting by Jane Chung Edited by Kenneth Maxwell and Jonathan Oatis)