It comes as a second P&O ferry was detained by maritime authorities over safety concerns.

The Pride of Kent was held in Dover on Monday night after the Maritime and Coastguard Agency carried out an inspection. 

The move comes days after another of its ferries, the European Causeway, was detained in Northern Ireland due to issues related to crew training and documents of the ship.

The Maritime and Coastguard Agency said: “Our surveyors are in the process of detaining the Pride of Kent. We are awaiting confirmation of all the detainable items.”

Mr Shapps said: “Safety will not be compromised and further checks will continue.”

Mick Lynch, general secretary of trade union RMT, said: “It’s rare enough for the MCA to impound a ferry but P&O have now had two in a week after the jobs carve up which speaks volumes about the dire state of their operation.”

The ferry operator has been under fire after sacking 800 seafarers earlier this month without carrying out consultation.

P&O previously said that it needs to cut staff costs to balance its books after losing £100m a year for the past two years. 

Its owner, DP World, recently reported record profits and proposed paying the government of Dubai a $275m (£210m) dividend.

To date, 757 sacked seafarers are in the process of accepting P&O’s redundancy offer, 430 of whom will receive their payment in April having already completed the paperwork.

Meanwhile, on Wednesday Mr Shapps is due to announce new measures to close an EU loophole that allowed P&O to proceed with the mass firings.

It will be announced alongside mandatory minimum wage for operators sailing into British ports.

P&O said: “We fully welcome the Government’s commitment to increasing the minimum wage for all seafarers working in British waters.

“From the outset we have called for a level playing field when it comes to pay and conditions on British ferry routes.”