SEOUL, Jan 31 (Reuters) - A small amount of crude oil leaked into the sea off the southern coast of South Korea on Friday after a pipeline operated by GS Caltex Corp was cracked, but the spillage had no impact on refinery production, the company said.
The crack and subsequent leak occurred at a quay off Yeosu, over 300 km (185 miles) south of Seoul, while the 160,000-tonne tanker Wuyi San was preparing to offload crude, spokesmen for GS Caltex and the Korea Coast Guard said.
A small volume of oil remaining in the pipeline leaked, but none spilled from the tanker, the spokesmen said.
The exact scale of the leak and damage is not yet known, they said, adding that a clean-up of the ocean and seashore involving some 70 public and private vessels would continue on Saturday.
The operator of the tanker could not immediately be reached for comment.
"About 60-70 percent of the clean-up work has been completed, and the work will continue tomorrow," the Korea Coast Guard spokesman told Reuters by telephone.
South Korea's GS Caltex, with a 775,000-barrels-per-day (bpd) refining capacity, is equally owned by Chevron Corp , the second-largest U.S. oil company, and South Korea's GS Energy, owned by GS Holdings.
The Prime Minister's Office said in a statement: "The cause of the accident should be verified thoroughly to prevent a recurrence, while conducting a rapid clean-up to keep the ocean from being contaminated during the Lunar New Year holidays."
In 2007, South Korea's worst oil spill occurred off the coast of Taean, when 10,500 metric tonnes spilled from a Hong Kong-registered tanker that had its hull punctured in a collision.
In November 2013, a small amount of oil leaked into the sea east of South Korea from a cracked pipeline run by the country's top refiner, SK Energy, owned by SK Innovation.