P&O Ferries has announced it will close its Liverpool-Dublin route at the end of the year.
The ferry giant has blamed a lack of availability to dock in Merseyside in 2024 as the reason behind the cancellation.
P&O also said talks to consider an alternative site for its Liverpool-Dublin service to operate from have been 'unsuccessful'.
In a statement, the company said: "Without agreement with the port owner to provide a berth in Liverpool, it is impossible for P&O Ferries to continue operating on this route.
"Extensive negotiations with the owner of our Liverpool site to extend our lease at the port or find an alternative site for our Liverpool-Dublin service to operate from have been unsuccessful.
"P&O Ferries is committed to serving our Irish Sea customers and has explored all options to continue sailing on this route.
"Unfortunately, despite utmost efforts by P&O Ferries to find a viable solution, no suitable alternative has been offered that would enable us to maintain the current service into 2024.
"We are saddened by our forced withdrawal from this route, which will reduce competition and the choice of sailings available to customers on a crossing where there is currently only one alternative operator."
P&O has two ferries which made the Liverpol-Dublin trip 24 times a week.
Both ferries are mainly used to transport freight between the UK and the Republic of Ireland.
The company says it now intends to redeploy the two boats on other routes, adding it is beginning a consultation process with its employees affected by the closure.
It continued: "We will offer support to affected colleagues to find alternative employment within our business, or where that is not possible, help to find employment elsewhere.
"We have also worked to ensure that where possible our customers affected by the intended closure of the Liverpool-Dublin route can access alternative services with other operators.
"We remain fully committed to serving customers on our Irish Sea crossing between our ports in Larne and Cairnryan, where we recently celebrated our 50th year of operations, and on our network around the UK."
In response, Unite national officer Bobby Morton said: “This is an important ferry service and its loss will be a huge blow to the people of Liverpool and Dublin.”
“Unite will now ensure that the affected workers are fully compensated for being made redundant and will also be providing assistance with finding them appropriate new employment opportunities.”
A spokesman for Peel Ports Group confirmed that the P&O Ferries service would no longer be calling into Liverpool when their existing contract expired at the end of 2023.