A court has ordered a South Korean fishing boat be forfeited to the New Zealand government after the ship's crew were convicted of dumping more than 400 tonnes of New Zealand quota fish during two trips off the South Island last year.

Five ROK officers on the Oyang 75 fishing boat were convicted in their absence in the Christhchurch District Court Friday, after evidence was heard over the last two weeks, Radio New Zealand reported.

Judge David Saunders ordered the vessel be forfeited, as it was now the property of the Crown (government).

Prosecuting lawyer Grant Fletcher said the verdict was still significant despite the fact that the guilty men were out of the country.

Fletcher said a payment in lieu of the vessel could be made if the owners do not want to give it up, according to the report.

Sentencing was scheduled for September 21.

Radio New Zealand reported that it was believed to be one of the largest cases of fish dumping in New Zealand.

Meanwhile, the Ministry for Primary Industries had seized another Oyang vessel, said the report.

The captain and factory manager on the Oyang 77 were charged with illegal fish dumping and with failing to declare the catch of a basking shark and making false returns or misreporting the vessel's catch.

They had a total of 11 charges against them.

The ministry informed Radio New Zealand that the two men were due to appear in court next month.