Sydney  - Oil from a damaged ship that soiled 60 kilometres of beaches on Australia's east coast will take weeks to remove, officials said Saturday.

There were also fears that 400 tons of ammonium nitrate lost overboard from the Hong Kong-registered Pacific Adventurer could create massive algal blooms in the ocean as the 31 lost containers leak over time.

Planes have been searching in vain for the lost containers from the air. Ammonium nitrate is used to manufacture fertilizer.

Oil sprang from the 180-metre vessel when containers tipped overboard in a storm holed the hull and pierced a fuel tank.

Owners Swire Shipping Ltd said when the accident happened Wednesday that 42 tons of marine diesel had leaked from the ship, which is now tied up in Brisbane harbour, but estimates of the actual amount go much higher.

Paul Lucas, deputy premier of Queensland state, said the scale of the environmental disaster could be 10 times the initial assessment.

"They originally told us 20 to 30 tons," Lucas said. "It's now apparent that it was about 230 tons."

Crews were cleaning beaches on Moreton Island, Bribie Island and the Sunshine Coast. The popular tourist haunts are closed during the cleaning.

Tourism Minister Desley Boyle said black sludge along formerly pristine beaches had prompted hotel-booking cancellations, but urged tourists to keep coming.

"This spill is something that will be cleaned up as quickly as possible and I expect to see people out on our beaches as we enjoy a beautiful Easter," she said. (dpa)