The sunken wreck of a wartime ocean liner north of Auckland is a disaster waiting to happen, environmentalists say.

The New Zealand ship RMS Niagara was sunk by a German mine in 1940. It has been sitting under the sea for 77 years, gradually rusting and seeping small amounts of oil into the water.

But the ship's main bunker tanks are still intact, and contain up to 2000 tonnes of oil.
There are fears the rusting wreck could suddenly collapse, spilling oil into the sea around Bream Head, by Whangarei.

Auckland Conservation Board chair Lyn Mayes said the board has asked government ministers to urgently assess the risk the wreck poses.


Mayes said the wreck is a ticking time bomb, which could have a huge impact on the area where threatened seabird species reside.

Speaking to Newstalk ZB's Larry Williams this afternoon Auckland Councillor Mike Lee said other wartime wrecks sunk near the Solomon Islands are already leaking. The RMS Niagara was sunk before those ships.

"We are told that with corrosion and biological bacterial activity that the bulkheads will erode away and gradually collapse."

The wreck is lying on its side and will gradually crush itself, he said.

New Zealand's oil spill contingency plans cover a six-tonne spill, Lee said. A 2000-tonne spill would be a disaster.

"I don't want to overcook it but at same time we don't want to underestimate the real risk."

He said there was concern Maritime NZ was not taking the risk seriously.

Lee said the first step was to get the wreck checked; if collapse was imminent, the oil could be removed and sea water pumped in to stop it from imploding.