A ferry company that operates Irish Sea services between Larne and Cairnryan is cutting more than 1,000 jobs.
P&O Ferries said it is part of a plan to make the business "viable and sustainable".
The ferry operator, based in Dover, Kent, also runs services between the UK and France, Belgium and the Netherlands.
The proposal involves more than a quarter of the workforce losing their jobs.
While the company would not confirm how many it currently employs in Larne, it's understood there will now be a consultation period which will look at all aspects of the business.
A spokesman for P&O Ferries said: "Since the beginning of the crisis, P&O Ferries has been working with its stakeholders to address the impact of the loss of the passenger business.
"It is now clear that right-sizing the business is necessary to create a viable and sustainable P&O Ferries to get through Covid-19.
"Regrettably, therefore, due to the reduced number of vessels we are operating and the ongoing downturn in business, we are beginning consultation proceedings with a proposal to make around 1,100 of our colleagues redundant."
Jobs are at risk across all levels of the business, owned by DP World, which is based in Dubai.
Before the pandemic, the Cairnryan to Larne ferry route ran up to seven times a day.
"This is a vital service, the only one operating out of Larne, and is important for quick transport of foods for supermarkets," said Seamus Leheny, policy manager at the Northern Ireland Freight Transport Association.
"It's possible that P&O will look at this link as viable and that job losses in Larne will be kept to a minimum.
"Last year 190,000 lorries travelled on the route and while it's going to be some time before we get back to that level, the service remains vital.
"Some 23% of all roll on roll off transport came to Northern Ireland through Larne.
"I would imagine the main target of the job losses would be in cross channel routes between England and Europe."
DUP MLA Gordon Lyons, who represents the area, said any job losses would have a big impact on the local community.
"Obviously I will work with my DUP colleagues to ensure the routes are maintained," he said.
"We need to have the ability to travel back and forward within the United Kingdom and we must do everything we can to prevent the devastating loss of jobs in the area.
"Northern Ireland is in a unique position. We do not have the channel tunnel link to mainland Europe.
"Ports are our main route of bringing freight into Northern Ireland and it's critical that the link is maintained to the highest standard possible."
It emerged in early April that P&O Ferries was seeking a £150m bailout from the UK Government to avoid collapse, but no offer was made. The firm's proposal was understood to be based on running its full complement of 21 ships.
But the company is now only operating 15 vessels, with reduced frequency, and remains hopeful of reaching an agreement with the government for a lower amount of money to secure critical supply routes.
It also emerged last month that DP World was set to pay shareholders a £270m dividend, a payment it's understood the firm was legally required to make.
P&O began operating ferries in the 1960s and the daily service provides a bridge for goods being transported between Northern Ireland and the Republic and Britain, and also on to the continent from England.
Mick Cash, general secretary of the RMT union, said it was "devastating news and an appalling betrayal of the P&O workforce".
"This is a kick in the teeth for P&O seafarers who have maintained key supply lines to the UK during the Covid-19 pandemic," he said.
"What is utterly shameful is P&O have been kept afloat by our members and the taxpayer whilst their owners have been paying out hundreds of millions in dividends in Dubai."