A P&O ferry has been detained in Larne, Northern Ireland, according to the Maritime and Coastguard Agency (MCA).
The agency said the ship, the European Causeway, was held “due to failures on crew familiarisation, vessel documentation and crew training”.
In a statement it said: “The vessel will remain under detention until all these issues are resolved by P&O Ferries.
“Only then will it be reinspected.”
The statement added: “Detention of ships is based on concerns over their safety and to prevent them going to sea.”
There were no passengers on board the vessel when it was detained, the MCA said.
Shapps says P&O will not be able to rush inexperienced crew through training
Transport Secretary Grant Shapps tweeted: “Following my instruction to inspect all P&O vessels prior to entering back into service, the Maritime and Coastguard Agency has detained a ship for being unfit to sail.
“I will not compromise the safety of these vessels and P&O will not be able to rush inexperienced crew through training.”
Mr Shapps had previously called on P&O Ferries’ chief executive Peter Hebblethwaite to quit over the sacking of almost 800 workers without notice.
The RMT union said it welcomed the detention of the European Causeway and it demanded the government “seize the entire fleet” of P&O vessels.
General secretary Mick Lynch said: “The seizing of the European Causeway by the MCA tonight shows that the gangster capitalist outfit P&O are not fit and proper to run a safe service after the jobs massacre.
“This mob should be barred, their ships impounded and the sacked crews reinstated to get these crucial ferry routes back running safely.”
The company replaced its crews with cheaper agency workers last week.
The chief executive admitted the new crews are being paid below the UK’s minimum wage – apart from those on domestic routes.
Mr Hebblethwaite said the average hourly pay of the new crew is only £5.50. The minimum wage in the UK for people aged 23 and above is £8.91 per hour.
On Thursday, he admitted the company broke employment law by failing to consult with unions and staff during evidence to a Parliamentary select committee.
However, he denied breaking criminal law in an email to remaining P&O staff on Friday, telling them they should not fear the same fate as their former colleagues.