Sydney  - The 31 containers lost overboard when the Pacific Adventurer was buffeted by a storm off Australia's east coast a week ago would be hard to recover, an expert said Wednesday.

The Navy mine hunter HMAS Yarra was sent to look for the lost boxes of ammonium nitrate after an aerial survey failed to find them.

Greg Boller from the ocean-monitoring firm Tide Tech said the containers could have travelled 700 kilometres from the scene of the accident and be nearer Sydney than Brisbane.

"But that doesn't mean they would be there," Boller told the national broadcaster ABC. "They may still be sitting in the waters near North Stradbroke," where they went overboard.

As well as losing half its cargo of containers, the Hong Kong-owned ship spilled oil over 60 kilometres of beaches.

Authorities have impounded the 180-metre vessel in Brisbane harbour and started legal proceedings against the captain and against owner Swire Shipping Ltd.

The Queensland state government is demanding compensation for having to clean up the oil spill and for any loss of tourism earnings through hotel room cancellations. It is also likely to bill Swire for the search for the lost boxes, which contain 620 tons of ammonium nitrate, an ingredient used to produce fertilizer. (dpa)