Protesters in London have called on the Government to nationalise P&O Ferries after the company sacked 800 seafarers without notice.
The staff were fired on Thursday and attempts are being made to replace them with cheaper agency workers.
Demonstrations have been held at ports in Liverpool, Larne, Hull and Dover, as unions call for a boycott of the company.
At least 100 protesters also gathered outside the officers of P&O Ferries’ owner DP World in Victoria, central London on Friday.
Members of the Rail, Maritime and Transport Workers union (RMT), Unite, Transport Salaried Staffs’ Association (TSSA) and Nautilus International joined the demonstration.
Protesters chanted: “Nationalise P&O”, “Seize the ships,” and “don’t go P&O” and “Solidarity forever”.
They also held up signs saying: “Save Our Seafarers” and “Stop the P&O jobs carve up”.
After speaking to the crowd, Steve Hedley, RMT senior associate general secretary, told the PA news agency: “It was one of the most brutal and appalling sackings I’ve witnessed in over 30 years as a trade unionist.
It is scandalous what has gone onFormer Labour leader Jeremy Corbyn
“We are absolutely furious.
“I mean if this can happen in Dover, this can happen anywhere.
“If this can happen with P&O, every rotten boss and capitalist in the country are going to be queuing up to do the same thing – sack all their staff and bring in staff on half their wages.”
Mr Hedley said workers were “in tears” on Thursday as “people who had worked there for 30 years were getting thrown off a ship at two hours notice”.
“These are workers who worked all the way through the pandemic, who were told they were essential workers, heroes, all the rest of it, when it comes down to it, discarded like trash,” he added.
Former Labour leader Jeremy Corbyn also spoke to protesters, telling the crowd: “What P&O have done is a disgrace and is disgusting by any standard.
“What we’ve got here is 800 well-qualified experienced skilled people who know how to operate those vehicles, know how to operate them safely and know how to care for the travelling public as well as the freight.
“And what have they been replaced with?
“People who have been brought in from goodness knows where to be paid a lot less – qualified or not? I have no idea and neither do you.”
Mr Corbyn later told PA that he shares the anger of the workers and the unions.
It was one of the most brutal and appalling sackings I've witnessed in over 30 years as a trade unionistSteve Hedley, RMT
He said that the Government should “intervene now”, but if that fails, it should nationalise P&O Ferries.
“I think P&O’s decision to get rid of 800 staff with no notice at all is a very, very, very bad sign,” Mr Corbyn said.
“You cannot have a famous name like P&O, an iconic name, treating its workers like this.
“This is shocking. Running a ship is a very skilled business and you have very experienced seafarers here who are all losing their jobs.
“It is scandalous what has gone on.”
P&O Ferries said in a statement: “We took this difficult decision as a last resort and only after full consideration of all other options but, ultimately, we concluded that the business wouldn’t survive without fundamentally changed crewing arrangements, which in turn would inevitably result in redundancies.”