New crew on P&O ships will be paid at rates well below the minimum wage, a union has claimed amid continued anger over the sacking of 800 workers by the ferry giant.

The Rail, Maritime and Transport union (RMT) said it had discovered another “shocking twist” to the scandal because replacement crews on P&O ships will be on “poverty pay”.

More demonstrations will be held in the next few days, with growing pressure on the company, which operates from Dover, to reverse its decision and the Government to take action.

The RMT said P&O ships on the Liverpool-Dublin route have now been crewed with Filipino ratings on contracts which pay below the minimum wage.

Shipping companies which are registered in other countries and operating routes from UK ports to Europe can pay below the minimum wage because they are exempt from legislation.

RMT general secretary Mick Lynch said: “The weakness in UK employment law has not only allowed the mass dismissing of UK seafarers it has also incentivised this barbaric behaviour because employers know there may be no effective sanction to stop them doing so, and on top of that they can get away with paying below the minimum wage.

“P&O may pay more than the minimum wage at first to agency staff but they will eventually move to rates below this simply because there is nothing to stop them from doing so.

“We fear poverty pay will be accompanied by seafarers being chained to 12-hour day, seven-day week contracts that operate continuously for six months, with no pension.”

The union has called for a boycott of P&O services and is urging the Government to look at legal options to reinstate the sacked workers.

Mr Lynch added: “We need new employment legislation to protect UK seafarers. The reason P&O have not been able to sack seafarers on Dutch and French contracts is because they have far stronger national employment laws.”

A demonstration will be held outside Parliament on Monday and at the P&O ferry terminal in Cairnryan, southern Scotland, on Wednesday.

TUC general secretary Frances O’Grady said: “There was no attempt to challenge P&O on these unconscionable tactics or even question whether these actions were legal.

“Ministers, from the Prime Minister down, have serious questions to answer.

“This a national scandal. It has to be a catalyst for change on workers’ rights.

“It’s time for the Government to urgently bring forward an employment Bill to stop workers from being treated like disposable labour and make sure what happened at P&O never happens again.

“P&O has acted appallingly. The company must immediate reinstate all sacked staff with no loss of pay.”

A spokesperson for P&O Ferries said: “We know that for our staff this redundancy came without warning or prior consultation, and we fully understand that this has caused distress for them and their families.

“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.

“We also took the view, in good faith, that reaching agreement on the way forward would be impossible and, against this background, that the process itself would be highly disruptive, not just for the business but for UK trade and tourism.

We have offered enhanced severance terms to those affected to properly and promptly compensate them for the lack of warning and consultation.

“The changes we’ve made bring us into line with standard industry practice.

“All affected crew who were working (at the time) were notified face-to-face and in-person on board their vessels.

“For crew who were off, P&O Ferries made all efforts to notify them personally: they were individually called on the phone, as well as via email and text.

“Virtual meetings were also held but only 261 of our 800 affected staff were on those calls.

“To try to minimise disruption for our customers, we contacted everyone we could reach.

“If any passengers have any queries about travelling with us, we encourage them to get in touch with our customer services team.

“The teams escorting the seafarers off our vessels were totally professional in handling this difficult task with all appropriate sensitivity.

“Contrary to rumours, none of our people wore balaclavas nor were they directed to use handcuffs nor force.”