A cargo ship that spilled 31 containers of ammonium nitrate into Moreton Bay, Queensland, in the wake of Cyclone Hamish, also leaked heavy fuel oil.
The Pacific Adventurer was travelling from Newcastle to Brisbane in rough seas near Point Lookout at Stradbroke Island in southeast Queensland when the container spill happened about 3am (AEST) on Wednesday.
Maritime Safety Queensland general manager Captain John Watkinson told ABC Radio a falling container damaged the ship's hull where the heavy fuel oil was stored.
Captain Watkinson could not say whether all the spilt containers would be retrieved.
The Australian Maritime Safety Authority said three tonnes of ammonium nitrate were spilt on the ship's deck. However, the containers, which contain granular ammonium nitrate, were sealed so it was unlikely they would leak.
The ammonium nitrate was believed to be of low toxicity and would not damage marine life.