At least 100,000 barrels of crude spilled into the Yellow Sea on Friday morning when a crane on the barge crashed into the Hebei Spirit tanker near Mallipo beach on Taean, south of Seoul.
The Yonhap news agency said more oil could leak into the sea as the accident had left three gashes in the hull of the tanker, capable of carrying over 1 million barrels.
The government has sent over two dozen ships to help with the clean up operation, but the slick is proving difficult to tackle amid four-meter waves and wind speeds of up to 18 meters per second.
The authorities fear an environmental disaster in the Taean Peninsula if the slick, within a 10 km range from the shore, is not contained within the next 48 hours.
The spill is the largest in Korean waters since 1995, when over 30,000 barrels of crude leaked into the sea off the country's south coast.
