An inspector for the National Offshore Petroleum Safety and Environmental Management Authority said Technip's failure to provide the rescue capabilities would involve an immediate threat to the health or safety of saturation divers in an emergency.

In the notice, NOPSEMA said work needed to stop immediately prior to the North Sea Atlantic departing the location of the Wellservicer facility, stationed near Onslow, or until a new vessel arrives on location of at least equal capability with respect to hyperbaric boat rescue as the North Sea Atlantic as described in the safety case in force for the Wellservicer facility.

The Wellservicer is a versatile multi-purpose vessel that combines heavy lift capability with either diver or diverless intervention support, while the North Sea Atlantic is a multi-purpose construction vessel for subsea work.

As its name suggests, when it was commissioned in 2014 it was envisaged to work predominantly in the North Sea, but is suitable for deepwater operations worldwide.

The 1989-built Wellservicer has a depth rating of 450m, and is certified for 300m. It has two diving bells and a dive chamber.

The Wellservicer was recently upgraded in Gibraltar, including an extensive overhaul of the ship's three tunnel thrusters and three azimuthing thrusters. The two small deck cranes were replaced with two brand new five tonne capacity units.

It arrived in Australia in October.

It is not the first time the Wellservicer has been involved in a safety issue.

In June Technip was fined $US250,000 ($A340,000) for the death of rigger David Stephenson in 2009.

Technip admitted a breach of the North Sea safety regulations during testing of the forward bell near Aberdeen.

It was found that there was a problem with the buoyancy blocks attached to the dive bell, which was touching the cursor frame and preventing the frame from fully engaging with the dive bell.

Stephenson put on a safety harness and a fall arrestor and climbed onto the top of the forward dive bell and, as he started to remove the bolts, the cursor descended towards the forward dive bell from a height of about 3m.

Stephenson tried to jump off the dive bell, but his safety harness locked and he was struck by the cursor and pinned down. He died in hospital shortly after.

An investigation by the UK's Maritime and Coastguard Agency concluded the cursor should have been prevented from descending by the braking system on the secondary winch but became ineffective for some reason.

The cursor was attached to a system that had not been properly approved, and it appeared to the MCA that the hazard posed by working under a suspended load and the potential for that to descend had not been recognised so additional control measures had not been put in place.

Technip declined to comment about the NOPSEMA prohibition notice.