SINAN -- An oil spill caused by a ship collision has contaminated the waters off the country's southwestern coast, the Korea Coast Guard said Thursday.

The accident occurred at around 3:30 p.m. Tuesday near a seawall construction site at a port in the southwestern island of Gageo, South Jeolla Province.

A 78-ton tugboat at the site crashed into a 800-ton barge and sank completely in two hours, according to the Mokpo office of the Korea Coast Guard.

The tugboat carried 24 tons of oil, including bunker fuel oil.

The Coast Guard, the county office and environmental activists have so far managed to clean up 8 tons of oil.

"We're concerned as the spilt oil can affect nearby fish farms and fishing operations," an official at the Sinan county government said.

Coast Guard authorities believe that the tug was holed after not being able to withstand the impact due to its old age.

The boat was salvaged Thursday and will be inspected to investigate the cause of the accident.

"The owner of the vessel argues that it had passed a safety test, but we're planning to review how a 60-year-old tugboat was used in the construction site in the beginning," a Coast Guard official said. (Yonhap)