The major shareholder in New Zealand's biggest oilfield has pleaded guilty to spilling 23,000 litres of oil off the Taranaki coast.
The spill occurred in October last year and crude oil remains lodged in rocks along 10km of coast near New Plymouth.
Maritime New Zealand charged Tui's shareholding operator, Australian Worldwide Exploration, and Prosafe, which runs the field's offshore production ship.
Australian Worldwide Exploration pleaded guilty in New Plymouth District Court on Thursday.
Prosafe expects to enter a guilty plea before sentencing in August. Each company could be fined up to $200,000.
The Tui partnership is pumping $7 million of oil a day, from a field worth $9 billion over its 15-year life at current prices.