There are claims an oil spill off the state's Kimberley coast has spread to an area estimated to be at least one-hundred times the size of Sydney Harbour.
Researchers from the World Wildlife Fund have found chunks of waxy substances from chemical dispersant floating on the surface.
WWF spokesman Jonathon Larkin says the government appears to assume there isn't much marine life in the area.
He says it'll be three weeks before the leak from the West Atlas rig is plugged.