Services were suspended and a series of demonstrations were expected to take place against P&O’s “appalling” decision to sack 800 seafarers.

Unions and politicians condemned the mass dismissal, blamed by the company on losses of £100 million following the slump in travel because of the pandemic.

The firm said early on Friday it would not be able to operate services “for the next few days” from Dover to Calais, Hull to Rotterdam, Liverpool to Dublin, and Cairnryan, Scotland, to Larne, Northern Ireland.

It advised those already at Dover and Calais to make their way to the check-in booths for Danish firm DFDS, but there were no such instructions for those at Hull, Rotterdam, Liverpool, Dublin, Cairnryan or Larne.

The Labour MP for Kingston upon Hull East called on the Government to force P&O to “come up with a different plan”.

Karl Turner told the BBC: “What I say to the Government is you’ve got to get P&O into a position where they’re prepared to negotiate with the trade union members.

“And they’ve got to come up with a different plan. They can’t just summarily dismiss people without any consultation or notice. It’s 800 jobs across the country.”

Earlier, the Rail, Maritime and Transport union (RMT) said it was seeking legal advice to challenge the sackings.

It said the UK has seen one of the most “vicious examples of despotic employer behaviour” and one of the most shameful episodes in its recent industrial history.

Announcing the decision on Thursday, the ferry operator, bought by Dubai-based logistics giant DP World in 2019, insisted the decision to cut jobs was “very difficult but necessary” as it was “not a viable business” in its current state.

The 800 workers were sacked immediately, with no notice, so they can be replaced by cheaper labour.

Security guards boarded ships with handcuffs to remove fired crew, it was alleged.

The union called for mass trade union and wider public support for demonstrations in Dover, Liverpool and Hull on Friday.

In a message to RMT members, general secretary Mick Lynch said: “It was with deep shock that I learned the news of the wholesale job cuts taking place at P&O Ferries, but I am sure that my shock was nothing as compared to the devastation this news brought to you and your colleagues.”

He added: “This appalling situation has arisen as a result of DP World wishing to maximise their profits and the failure of the Government to intervene and protect the jobs of you and your colleagues.”

Conservative MP Huw Merriman, chairman of the Transport Select Committee, said P&O had shown “contempt” for its staff.

“If they do not reverse immediately and reinstate the employees and follow proper process, it’s hard to see a way back for them commercially,” he said.

“The parent DP World needs to understand that the British public will not do business with companies who treat their employees with such contempt.”

Shadow transport secretary Louise Haigh said: “This is not a corporate restructure. It’s not the way we go about business in this country.

“It is beneath contempt; the action of thugs.”

P&O Ferries said in a statement: “We have made a £100 million 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.”