BRISBANE, Australia - Officials declared 60 kilometres of oil-blackened beaches along Australia's east coast a disaster zone on Friday, and warned of legal action against the operator of the cargo ship that spilled its fuel load in stormy seas.

Authorities said about 30 tonnes of oil were lost when containers slipped from the Pacific Adventurer ship and punctured fuel stores in the hull as it rocked in cyclone-stirred waters Wednesday.

Queensland state Premier Anna Bligh said Friday the spill was larger than had been reported earlier but did not say how much oil was lost. Her office said they did not have definite numbers yet.

Bligh declared some 60 kilometres of normally white-sand beaches along the popular surf region of the Sunshine Coast a disaster zone, as well as Moreton and Bribie islands, which are national parks.

At Coolum, about 100 kilometres north of the state capital of Brisbane, dark brown waves rolled ashore instead of the usual whitecaps and aqua waters of the Coral Sea.

Stung by criticism that the clean-up effort was slow to get started, Bligh said initial reports that the slick did not pose a large environmental threat were wrong.

"The full extent only became obvious yesterday with aerial surveillance," Bligh told Nine Network television. "This can't be cleaned up until it actually hits the beaches and that's what's happening at the moment."

Swire Shipping, which operates the Pacific Adventurer, said the ship had been holding about 1,190 tonnes of oil when it set sail on Tuesday from Newcastle, a port about 610 kilometres south of Brisbane.

Bligh said the ship's operators would be held liable for the costs of the cleanup operation.

"We are investigating the entire incident and if there is any basis for a prosecution, we will not hesitate to take that action," she said. "The total cost of the cleanup will rest with this company."

At Buddina Beach, about 45 kilometres north of Brisbane, workers raked up oil-coated sand, while wildlife officials tried to catch and clean birds coated with oil. Resident Vicki Ayliffe bemoaned the lack of a coordinated response to the spill.

"This is our beach. I've been coming here for years, and it's sad to see this happen here," Ayliffe said as she picked up soft drink containers and milk cartons coated with oil.

Declaring the area a disaster zone empowers police and authorities to close beaches and restrict access.

The Environment Protection Agency was concerned about the spill's impact on wildlife but said Friday only 13 oil-affected animals had been spotted. Spokesman Clive Cook said agency workers had caught and cleaned three of those -- a pelican, a turtle and a wading bird.

"At the moment we're very lucky ... but obviously in these circumstances we're worried it might escalate," he said.