---

A cargo ship that lost 31 containers of ammonium nitrate in Queensland's Moreton Bay in the wake of Cyclone Hamish has also leaked heavy fuel oil.

The Hong Kong-flagged Pacific Adventurer was travelling from Newcastle to Brisbane in rough seas when the containers broke loose on Wednesday morning in waters off Point Lookout on Stradbroke Island at approximately 3am.

Maritime Safety Queensland general manager Captain John Watkinson said a falling container had also damaged the ship's hull where the heavy fuel oil was stored, causing the bunker fuel to leak into the open sea.

"One of the containers as it went over the side, with the movement of the ship, has pierced the hull,'' Watkinson told ABC Radio.

"So the ship has lost a little heavy fuel oil. No one has been harmed as far as we're aware," he added.

A spokesman for charter company Swire Shipping said "There has been a small spillage of fuel oil from a damaged tank. The crew has transferred all oil from the damaged tank to other tanks and no further oil is spilling."

Commenting on the lost containers of ammonium nitrate, used for making fertilizer and explosives, John Watkinson could not say whether all the containers would be retrieved.

"The ship's master indicated that he thought the containers had sunk. The other (possibility) is that they're still floating around out there. We've got a plane or chopper going out there soon," said Watkinson.

Three tons of ammonium nitrate spilled on the ship's deck when the containers broke loose, Australian Maritime Safety Authority (AMSA) spokeswoman Tracey Jiggins said, adding that as the containers were sealed, it was unikely that they would leak.

Jigging said AMSA's environmental protection response team also believed the ammonium nitrate was of low toxicity and wouldn't damage marine life. In contrast, however, marine biologist Dr Norm Duke from the University of Queensland said the episode was of concern.

Speaking to ABC News, Duke said that if the containers were to leak, they could cause a toxic bloom of phytoplankton, the basis of the ocean's plant ecosystem, which in turn could harm marine life in Moreton Bay.