Cross-Channel ferry operators will be required to pay their crew at least £9.95 an hour after France implemented a new minimum wage law aimed at preventing the exploitation of seafarers.

The move comes two years after P&O Ferries caused outrage on both sides of the Channel by sacking almost 800 workers and replacing them with low-cost crew.

The Guardian and ITV News reported on Monday how P&O’s replacement crew appeared to be paid average hourly rates of about £4.87 – even lower than the £5.15 an hour P&O told a parliamentary select committee was its lowest pay rate in March 2022.

The low rates have been achieved lawfully by P&O, which has taken advantage of legal loopholes that exempt paying the minimum wage to maritime workers employed by an overseas agency and working on foreign-registered ships in international waters.

As part of its response to P&O’s 2022 sackings, France signed a decree on Tuesday to enact legislation that will force cross-Channel operators to pay their workers the French minimum wage of at least €11.65 (£9.95) an hour.

Hervé Berville, France’s maritime minister, told the Guardian and ITV News: “We changed the law because we were really shocked by what happened in March 2022.

“We couldn’t accept that a company can sack 800 seafarers like this. So we needed to do something. Not only react, but show that politics, show that government, has to act to protect citizens and the seafarers.”

Berville said the law was designed to apply to all operators serving cross-Channel routes, such as Dover to Calais and Poole to Cherbourg. He added that the highest minimum wage would apply.

Apart from setting a minimum level of pay, France’s new law will restrict crew from working on ferries for longer than two weeks without a day off.

P&O crew members interviewed by the Guardian and ITV News said they worked 12-hour shifts, seven days a week, for up to 17 weeks at a time. The workers said they must remain on the ship until their contract ends.

Before the new French legislation bites, operators will be given a three-month implementation period. Rival ferry groups paying at least minimum wage fear that during that window P&O and another low-cost operator, Irish Ferries, may launch a legal challenge.

Similar legislation in the UK to prevent crew being paid less than the minimum wage is expected to come into force this summer. The UK minimum wage now stands at £10.42 an hour and will rise to £11.44 an hour from April.

Once both laws become active, any ferry company found to be paying less than the minimum wage could be fined about £76,000 a day – roughly split equally between fines by UK and French authorities – according to an analysis by Brittany Ferries, which has not adopted a low-cost business model.

Neither P&O nor Irish Ferries answered questions about whether they would appeal against the French law.

A spokesperson for P&O has previously told the Guardian that the company pays its cross-Channel crew members at least £5.20 an hour and added: “We always pay at least the minimum wage required by national and international law.

“We provide an industry-leading support package and work hard to ensure their welfare, wellbeing and mental health are properly cared for.”

A spokesperson for Irish Ferries said the company’s lowest-paid crew were on rates that equated to less than £9 an hour. “Whatever the regulatory framework, Irish Ferries is committed to compliance, whilst continuing to work hard to make its operations as efficient as possible.

“Our practices, especially concerning crew rest times, have recently undergone independent rigorous analysis and review by leaders in this field, affirming our commitment to safety and operational excellence.”