THE full scale of the environmental disaster off the Queensland coast has become clearer as the shipping company admitted its earlier estimates of the oil spill's size were "substantially" wrong and the length and the cost of the clean-up were revised upwards by the State Government.

An oil slick measuring tens of kilometres is staining the shore along Sunshine Coast beaches, Bribie Island and Moreton Island.

A nature conservation officer carries a pelican, covered in oil, from the beach on Moreton Island. Credit:Tertius Pickard

The cargo vessel Pacific Adventurer leaked the oil late yesterday from a hull breach as it lay moored in Brisbane's port. It was a casualty of rough seas it had encountered on a voyage to Indonesia on Wednesday.

"I think it's fair to say the Government and authorities were not informed accurately of the size of the spill," said Allan Sutherland, the Mayor of Moreton Bay Regional Council, where part of the clean-up was taking place. "[Swire Shipping] were hoping Mother Nature would take its course. It didn't."