A P&O Ferries ship that serves the Scotland to Northern Ireland route has been detained for being “unfit to sail”.
The European Causeway vessel has been held in Larne due to “failures on crew familiarisation, vessel documentation and crew training”, the Maritime and Coastguard Agency (MCA) said.
The ship is one of two that runs from Cairnryan to Larne but all sailings have been suspended following the mass sacking of crew. The European Highlander remains in port at Cairnryan.
Transport secretary Grant Shapps said P&O Ferries will not be able to rush training for inexperienced people.
The company sacked almost 800 seafarers as part of a plan to replace them with agency staff on cheaper salaries.
A spokesperson for the Maritime and Coastguard Agency said: “We can confirm that the European Causeway has been detained in Larne.
“It has been detained due to failures on crew familiarisation, vessel documentation and crew training.
“The vessel will remain under detention until all these issues are resolved by P&O Ferries. Only then will it be reinspected.”
The MCA said there were no passengers or freight on board the European Causeway vessel when it was detained.
Shapps said: “Following my instruction to inspect all P&O vessels prior to entering back into service, the [Coastguard] 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.”
P&O Ferries said Cairnryan to Larne services remain suspended in an update that announced it was “no longer possible” for it to arrange travel via an alternative operator on the route.
“For essential travel, customers are advised to seek alternatives themselves,” the update said.
The European Causeway entered service in 2000 replacing the Pride of Rathlin, according to the P&O Ferries website.
“Specifically designed for our Cairnryan to Larne route, she has not operated elsewhere and has only been taken out of service if she needs a refit,” the website said.
Talks between union officials and P&O over the sacking of seafarers ended after 20 minutes without any agreement on Friday.
The company said it “wholly refuted” the Rail, Maritime and Transport union’s suggestion that its actions were illegal.
However, on Thursday, the boss of the embattled ferry operator admitted failing to consult unions over the decision to sack almost 800 workers on the spot broke the law.