Private security officers were sent on to a P&O ferry in Larne to remove workers protesting the sacking of more than 800 sailing staff, unions representatives have said.
Services between Larne and Cairnryan are suspended and will not resume for the “next few days”, the company said amid the turmoil that followed the shock announcement.
Approximately 100 seafarers working the Larne-Cairnryan route were among those sacked without notice on Thursday.
It is not clear if any staff were removed from the ship by security personnel, who were pictured stepping on-board.
Unions have told members it is in their best interests to stay on-board during this stand-off - but it is understood all staff have now left the ship. It is reported that the company, which wants to reduce its crew costs by 50%, plans to employ agency workers as replacements.
Passengers, hauliers and cargo were redirected to Stena Line ferries, including from Stranraer to Belfast, with the company saying it is trying to accommodate them but are extremely busy.
Politicians have told of their surprise at the developments, while it also caught industry insiders and hauliers completely by surprise.
In a statement, issued some hours after sailings were suspended and amid speculation, P&O said its business was not viable in its current state.
"P&O Ferries plays a critical role in keeping trade flowing, supply chains moving, and connecting families and friends across the North and Irish seas and the English Channel," it said.
The statement added: "However, in its current state, P&O Ferries is not a viable business. We have made a £100m loss year on year, which has been covered by our parent DP World. This is not sustainable. Our survival is dependent on making swift and significant changes now. Without these changes, there is no future for P&O Ferries.
"These circumstances have resulted in a very difficult but necessary decision, which was only taken after seriously considering all the available options. As part of the process we are starting today, we are providing 800 seafarers with immediate severance notices and will be compensating them for this lack of advance notice with enhanced compensation packages."
The company employs 3,000 people after making 1,100 redundant in May 2020. Dubai-based DP World bought P&O for £322m in 2019.
Alliance East Antrim MLA Stewart Dickson said urgent clarification is needed over the future of Larne Harbour. P&O owns the harbour and Mr Dickson said the local impact could be vast.
“My first thought is with the workers who have been informed by P&O they are no longer employed and I hope they get the support needed at this difficult time,” Mr Dickson said.
“I am deeply disappointed in how P&O have handled this entire episode, showing underhanded behaviour which is not acceptable at best and draconian measures to remove staff at worst. There appears to have been no consultation done with staff or unions over this move.
“Given that P&O owns Larne Harbour, urgent questions now need asked as to the potentially vast impact locally. I am calling on the Department for the Economy to engage immediately with P&O over the future of the harbour and any potential ramifications for it.”
East Antrim MP Sammy Wilson said: "This is a worrying development which has understandably shocked P&O staff and customers. I will speak to the chief executive of P&O for an update."
Stena Line confirmed it is trying to accommodate those booked on the P&O ferries between Scotland and Northern Ireland.
"We are reminding people that if they cannot get space on one of our six daily departures from Belfast, then we also have options via our services running from Dublin to Holyhead and even via Rosslare to Fishguard if people are travelling further south," Stena Line said.
The RMT union said it has instructed members to stay on-board their vessels once they have docked or risk being "locked out" of their jobs.
"We are digging in for the long-haul. We are determined to fight," RMT spokesperson Geoff Martin said.
The union said a private security team was sent on to a ship docked in Larne to remove staff on-board.
A "deeply disturbed” RMT general secretary Mick Lynch added: "We have instructed our members to remain on-board and are demanding our members across P&O’s UK operations are protected and that the Secretary of State intervenes to save UK seafarers from the dole queue.”
Mark Dickinson, general secretary of Nautilus International, which also represents seafarers, said the news "is a betrayal of British workers. It is nothing short of scandalous given that this Dubai-owned company received millions of pounds of British taxpayer’s money during the pandemic”.
He added: "There was no consultation and no notice given by P&O. Be assured, the full resources of Nautilus International stand ready to act in defence of our members. We believe it is in our members’ best interests to stay on-board until further notice.”