Newcastle Port Corporation chief executive Gary Webb said yesterday an investigation into the spill could result in charges being laid under the act, which was part of the NSW legal system.

As well as the corporate charges, the Marine Pollution Act had potential fines of up to $500,000 for individuals found guilty of ‘‘causing a discharge of substances into state waters’’.

The past week’s clean-up at Kooragang began after a coal ship, the Magdalene, allegedly and accidentally discharged tonnes of oil into the Port of Newcastle last Wednesday afternoon.

Mr Webb said clean-up crews had recovered about 12tonnes of oil, and calculations were under way to determine how much oil, in total, had been mixed with ballast water and discharged into the harbour.

Mr Webb said the 30-person clean-up effort was concentrating on removing as much oil as possible from the water and the shoreline, and on looking after the pelicans contaminated with the oil.

National Parks and Wildlife Service biodiversity officer Doug Beckers said 19 oil-affected pelicans were caught for treatment between Friday and yesterday.

Mr Beckers said the worst-affected birds were sent to Taronga Park Zoo for treatment but all would need to convalesce for at least two to three weeks.

‘‘Cleaning the oil from their feathers also removes their natural oil coating, which must have time to form again,’’ Mr Beckers said yesterday.