More than 1,64,000 litres of crude oil spilt into the sea after a Singapore-registered tanker, Wu Yi San, hit a pier and pierced a pipeline operated by a refiner.
There was no leak of crude from the tanker itself, but a 10-kilometre stretch of coastline was affected by the incident, causing damage to fish farms.
Fisheries Minister Yoon Jin-Sook sparked an uproar after she said the primary victim of the accident was the refiner and not local fishermen.
The 59-year-old minister later clarified that she was suffering from flu at the time, local media reported.
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Hundreds of private, coastguard and naval vessels have been involved in the clean-up but Yoon has faced criticism for what was seen as a slow response to the spill.
South Korea's worst oil spill was in 2007 when 10,500 tonnes of crude poured out of a Hong Kong-registered supertanker after a collision with a Samsung Heavy Industries barge near the western port of Taean.