A court Wednesday jailed the Indian captain and chief officer of a Hong Kong supertanker after ruling they were partly to blame for South Korea's worst oil spill.

The appeal court, overturning a lower court ruling, found the Hebei Spirit's top officers failed to take prompt action to reduce the spillage on December 7 last year which fouled miles of beaches.

Captain Jasprit Chawla was sentenced to 18 months in prison and fined 20 million won (14,000 dollars) while chief officer Syam Chetan was sentenced to eight months and fined 10 million won, court officials told AFP.

The pair were immediately taken into custody. Their lawyers said they would appeal to the supreme court.

The ship's owner, Hong Kong-registered Hebei Ocean Shipping, was fined 30 million won.

The ruling was likely to spark anger among international shipping operators and seafarer unions, who insist the tanker crew were blameless. The lower court in June had found them not guilty.

The International Association of Independent Tanker Owners in a statement expressed "extreme dismay and disappointment" at the ruling.

The accident happened when a barge carrying a construction crane broke free after a cable to one of two tugs snapped in rough seas.

The barge, owned by Samsung Heavy Industries, rammed the anchored 147,000-ton Hebei Spirit. It holed it in three places and spilt 10,900 tons of crude oil.

The appeal court in the central city of Daejeon confirmed guilty verdicts passed in June on the South Korean tugboat skippers but reduced their prison terms.

One was jailed for two years and six months, instead of three years previously. The other was jailed for eight months compared to an original one year.

The court confirmed a fine of 30 million won on Samsung Heavy Industries, part of the country's biggest business group. It ordered the barge captain, who had previously been exonerated, to be jailed for 18 months.

Scores of marine farms and miles of beaches, notably in Taean county about 110 kilometres (70 miles) southwest of Seoul, were smothered in oil by the spillage.

About 100 residents affected by the slick clapped and shouted "Mansei" (Hurray!) outside the appeal court, an AFP photographer saw.

"We are satisfied with the verdict," one said.

A spokesman for ship manager V Ships called the ruling technically flawed.

"All of the parties related to the Hebei Spirit are very disappointed and find the reasons given for the decision technically flawed," he said in a statement. "We are considering our options."

The court said the skipper and others on the tanker were negligent in efforts to minimise the oil spill right after the accident.

Judge Bang Seung-Man said the skipper and his crew took three and half hours to transfer oil from the leaking holds.

They also injected cooling gas into the holds to prevent an explosion but this only increased the amount of oil spilt, he said.

"The towing vessels share the greatest responsibility for the collision itself," the judge said.

Despite being cleared in June, Captain Chawla and Chief Officer Chetan had been banned from leaving South Korea, although they were not taken into custody until Wednesday.

Eight world shipping organisations in July protested against "the continuing unjust and unreasonable detention (in Korea)" of the pair and appealed to the government to let them leave.