The wreckage of a 70-year-old ship that was struck and sunk by a Japanese torpedo during World War II has been found off the coast of northern NSW.

The cargo ship, named MV Limerick, was part of a coastal wartime convoy travelling from Sydney to Brisbane when it was struck on ANZAC Day, 1943 by Japanese submarines.

The ship sank the following day, spewing its 72 crew members into the ocean.

Two of the ship's crew were killed, and the 70 others rescued.

"Limerick was one of the largest vessels sunk by Japanese submarines off Australia's east coast during their offensive submarine patrols through 1942 and 1943," NSW Heritage Minister Robyn Parker said in a statement.

The vessel has been missing for almost 70 years and was located by local fisherman near the NSW town of Ballina at the end of last year.

Australia's Marine National Facility then conducted a research voyage to locate the shipwreck.

Ms Parker said the loved ones of the men who lost their lives on MV Limerick will be notified.

"This is a reminder of the huge sacrifice paid by merchant seamen during the war on the home front keeping food, materials and supplies going," she said.

The shipwreck will be protected under the provisions of the Historic Shipwrecks Act.