A "comprehensive package of measures to ensure that seafarers are protected" are to be brought before Parliament in the wake of P&O Ferries sacking 800 UK workers without notice.
In a latter to P&O boss Peter Hebblethwaite, Transport Secretary Grant Shapps added he intends to block the "outcome that P&O Ferries has pursued", including paying workers less than the minimum wage.
He also called on the CEO to drop the deadline of March 31 "imposed on seafarers" to respond to redundancy offers
In the letter, Mr Shapps said: "The past week has left the reputation of P&O Ferries and, I'm afraid, you personally in tatters.
"Not only were your letters of 22 March to the Business Secretary and myself wholly unsatisfactory, your appearance at the Transport Select Committee, during which you brazenly admitted to breaking employment law, demonstrated beyond doubt your contempt for workers who have given years of service to your company.
"There is no excuse for this behaviour, and as I said publicly on Friday, I believe your position as chief executive, and indeed as a company director, has become untenable.
"On top of reviewing contracts you hold with government and asking the Insolvency Service to investigate your actions, this week I will go further.
"I will be bringing a comprehensive package of measures to Parliament to ensure that seafarers are protected against these types of actions in the way that Parliament and this Government already intended.
"Through that package, I intend to block the outcome that P&O Ferries has pursued, including paying workers less than the minimum wage."
He also called on Mr Hebblethwaite to offer "all 800 workers their jobs back on their previous terms, conditions and wages."
He added: "To be clear, our package of measures will prevent the law being broke, even when knowingly attempted.
"With this point in mind, I would also suggest that the deadlines improved on seafarers to respond to your redundancy offer by 31st March is dropped.
"Given that we intend to ensure outcomes are prevented by laws - which we will ensure that you cannot simply choose to ignore - I believe you will be left with little choice but to reverse your decision in any case.
"A reversal at this point may also go some way in starting to repair your firm's reputation with the public, many of whom will show their own disgust at your treatment of workers by simply choosing an alternative operator.
"P&O Ferries has a long and proud history. We are keen to help you rebuild the trust that has been lost.
"This government will not stand by while the requirement to treat seafarers with due respect and fairness is brazenly ignored."
A P&O Ferries spokesman 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.
"Our announcement is not about reducing seafarer's wages, it is to enable us to have a fully flexible crewing model that allows us to meet the demands of our customers.
"The predicted savings we announced are not solely coming from the reduction in wages, but from removing job duplication and the benefits we will see from increased flexibility."
