A 250-metre exclusion zone has been implemented by the Darwin Harbour Master after divers discovered a suspected unexploded bomb near the site of the new ship lift project.

The notice – which includes a mapped location and the exclusion zone, marked by yellow floating buoys in the harbour with flashing yellow lights – for Mariners has been posted.

The suspected unexploded ordinance, or UXO, was located 330m to the south of the Darwin Harbour’s multi-user barge ramp by divers with Commercial Marine Group.

The company was completing diving survey operations as part of work commissioned by the NT Government to search for leftover UXOs and other potential heritage items from World War II near the site of the $515 million ship lift project.

The Australian Defence Force is now planning for the safe disposal of the UXO, the government said. Dive works in the area have been suspended until further notice.

Sub-contracting company Aurecon, who found the UXO on Monday afternoon, reported the discovery to the ADF, NT Police and the Acting Regional Harbour Master (A/RHM).

The public notice of an exclusion zone was not sent out until late Tuesday afternoon.

DIPL is presently working with relevant stakeholders to ensure the safety of harbour users in the area, the government said.

Regular patrols of the harbour are also being made by the NT Water Police.

Vessels or persons found within the exclusion zone will be fined or escorted away from the area by water police officers.