The former shadow secretary for Northern Ireland has said "it’s time to throw the book” at P&O, after one of its ships suffered a mechanical failure, leaving it adrift off the coast of Larne.
Louise Haigh was responding to reports that a number of agency workers onboard the P&O ferry are also refusing to work on the ship.
The European Causeway is to remain at Larne Port until further inspections are carried out.
Passengers on the firm’s European Causeway were in a state of confusion after the ship was left drifting five miles out into the Irish Sea for more than an hour on Monday after setting sail for Scotland, before being docked in Co Antrim.
Afterwards a number of the ship’s new crew members asked maritime unions for advice about terminating their contracts due to their own safety concerns, according to The Times.
P&O have been contacted for a response to Ms Haigh’s latest comments.
Last month, the firm sacked nearly 800 workers without notice before announcing it would offer more than £36 million in compensation.
The Maritime And Coastguard Agency (MCA) said on Wednesday the ferry will have to stay docked until it is reviewed.
The agency also detained the vessel in March after it failed safety checks, but said there were no concerns for passengers' safety at any point during yesterday’s incident.
The coastguard was on standby in case support was needed, and the RNLI sent three lifeboats to the scene.
A trade union has since stated that no P&O ferry should be allowed to set sail after the incident.
P&O Ferries confirmed the ship, which can carry up to 410 passengers, continued its scheduled journey “under its own propulsion”, saying there were no concerns over passenger safety.
A service scheduled for 8pm last night had to be cancelled “due to technical difficulties”.
RMT general secretary Mick Lynch said “no P&O ferry should set sail on safety grounds”.
He added: “Staffing ferries with under-trained, ill-equipped, over-worked and grossly underpaid seafarers blatantly undermines maritime safety. There will be more safety-related incidents on the P&O fleet under these intolerable owners. We can only hope that they do not escalate in seriousness.
“Instead of taking that gamble with worker and passenger safety, the government must step in now and take over the running of all P&O vessels.”
Speaking to the Belfast Telegraph after the ship docked, passenger Patrick McFadden said everything “went black” after it lost power.
He explained there was confusion among passengers and claimed staff had failed to provide adequate information about what was happening.
“The tugboats started appearing, but nobody told us this. A big cruise ship was passing us, and that turned around,” Mr McFadden said.
“Then a helicopter appeared, and that’s when people started to wonder what was happening. There were probably four or five tugboats.
“This lasted around two hours. Nobody knew anybody, so everyone was quiet.
“Everyone was jumping about from one side of the ship to the other to see what was happening, but nobody told us.
“They [didn’t say] anything, [but then] they got the engines going.”
P&O Ferries said the incident would be investigated.
A spokesman added: “Following a temporary mechanical issue, the European Causeway is now continuing on its scheduled journey to the Port of Larne under its own propulsion, with local tugs on standby, where it will discharge its passengers and cargo as planned.
“There are no reported injuries on board and all the relevant authorities have been informed. Once in dock, an independent investigation will be undertaken.”
Yesterday, UK Transport secretary Grant Shapps said he thinks the company should pay back the £11m in furlough money they had access to and the British government are still looking to tighten laws around shipping in the upcoming Queen’s Speech.