The Royal Australian Navy is investigating a wreck found off Papua New Guinea which could be a World War II submarine.

The uncharted wreck was discovered in Simpson Harbour by a New Zealand navy survey ship and Australian minehunter HMAS Gascoyne.

The area was known for submarine operations during World War II.

Officials from the US, Japan, PNG and New Zealand have been informed of the discovery, and work is being done to identify the type and origin of the vessel.

The Australian and New Zealand navies were taking part in Operation Render Safe at the time the wreck was found.

The operation is part of the Australian Defence Force's contribution to enduring explosive ordnance disposal support to the nations of the south-west Pacific.

ABC/AAP