Thousands of people, some battling headaches and nausea from the stench of crude oil, used shovels and buckets to clean the muck from a once-scenic beach Sunday after South Korea's worst oil spill.

About 7,500 people including Coast Guard, police and military personnel, as well as civil servants and volunteers, were scooping up oil that began washing ashore at Mallipo beach a day earlier from a damaged supertanker, the Coast Guard said.

Still more worked aboard 105 ships along South Korea's western coast trying to clean the water. Mallipo is about 150 kilometres southwest of Seoul.

"We are working hard and making progress in the cleanup operation," said Kim Woon-tae, a regional Coast Guard official.

The Coast Guard said the last of three leaks in the Hong Kong-registered supertanker Hebei Spirit, rammed Friday by an out-of-control South Korean barge, had been plugged Sunday and the extent of affected coastline remained stable at 17 kilometres.

A total of 66,000 barrels (10.5 million litres) of crude gushed into the ocean, more than twice as much as in South Korea's worst previous spill in 1995.

Kim Sun-seon, who works for an ocean cleanup business in Busan, on South Korea's southeast coast, wore rubber gloves - and a mask to help cope with the strong smell of crude.

"We don't know when we can finish this work," she said. "We have been shoveling oil since yesterday, but the waves just keep bringing more oil. I feel dizzy."

At sea, Coast Guard personnel used a special oil fence to try keeping more crude from coming ashore. Mats to absorb oil were placed on the beach.

Oil began slopping onto the area's beaches after a barge came loose from a tugboat in rough seas and slammed into the tanker. Waves of crude turned seagulls black and threatened fish farms along the coast.

Mallipo, one of South Korea's most scenic beaches, is an important stopover for migrating birds such as snipe, mallards and great crested grebes, and has an abundant fishing industry.

Choi Kyung-hwan, a fisherman, came to help the cleanup, but despaired for the area where he has lived for 30 years.

"Mallipo is finished," he said, referring to the disaster's economic impact.

Choi said the oil had sickened his wife, and he was struggling with dizziness.

The affected area includes 181 aquatic farms producing abalone, seaweed, littleneck clams and sea cucumbers, said Lee Seung-yop, an official with the government of Taean County, where the beach is located.

The area has about 4,000 aquatic farmers, he said.

"A lot of damage is feared to these farms, although we don't have an estimate yet," Lee said.

About 63,800 people live in Taean. Fishing, fish farming and tourism are the major industries.

More than 20.6 million tourists visited the area last year, and at least 18 million had arrived as of the end of September this year, according to county statistics.

Local raw fish restaurants, like Lee Ok-hwa's, were suffering.

"I haven't had any customers since news of the oil spill Friday," said Lee, who had previously served 200 people a day.

"I don't know how to make a living," she said. "I don't know how to pay the rent. I believe this situation will last for at least one year."

The central government has designated the oil spill a "disaster," which makes it easier for regional governments to mobilize personnel, equipment and material to cope with the situation. Despite pleas to do so, however, it stopped short of declaring the region a "disaster area" - which would make residents eligible for government financial aid.

In Seoul, Prime Minister Han Duck-soo presided over a meeting with related ministries on the oil spill, said Song Ki-jin, an official at the prime minister's office. No details were given.

The accident occurred about 11 kilometres off Mallipo beach. The area also includes a national maritime park, where oil from the spill also washed ashore.

The Coast Guard said it was unclear how long the cleanup operation would last.

The tanker had been at anchor and carrying about 1.8 million barrels of crude oil to be loaded into boats from a nearby port. Neither the tanker nor barge was in danger of sinking, and no casualties were reported in the collision.