Sydney  - A container vessel lost half its load of industrial chemicals Wednesday in rough seas off Australia's east coast.

The Hong Kong-owned 180-metre Pacific Adventurer was brought to anchor in Moreton Bay near Brisbane.

Authorities in Queensland said more serious than 31 containers of ammonium nitrate falling overboard was a fuel oil spill when one of the tumbling boxes punctured a fuel tank and caused marine diesel to flood into the bay.

Aerial searches had failed to locate any of the containers.

Michael Short from the Environmental Protection Agency said the oil slick was a primary concern.

"There is oil on the surface so that can have an impact on beach environments and wildlife, so that's where our focus is," he said.

But Michael White from the Centre of Marine Studies at the University of Queensland told national broadcaster ABC that ammonium nitrate, an ingredient in fertilizer, was not a threat to marine life.

He warned that containers bobbing just below the ocean's surface could pose a serious threat for small boats in the bay.

"It's a hazard then, because if especially small craft come onto it, especially in heavy weather like now, they would bash the hull against the container and probably would break up the ship," he said. (dpa)