Meanwhile Kwasi Kwarteng, the Business Secretary, also warned P&O it may have breached its legal duties by failing to inform him in advance of the sackings and demanded that it answer a series of questions by 5pm on Tuesday.

DP World is investing £300m in an expansion of the London Gateway, which would be part of the Thames freeport, and is the owner of the Port of Southampton’s deep water terminal, making it a major player in the Solent freeport.

Labour and the RMT union have called for DP World’s involvement in Government contracts, including the freeport schemes, to be scrapped.

There are also concerns about a deficit in P&O’s pension fund, to which the company has not made any voluntary contributions since 2006.

Calls to review DP World’s freeport roles have not been welcomed in all quarters, however, with Southampton Itchen MP Royston Smith warning that Labour may be “jumping the gun”.

The Tory backbencher said DP World had acted “despicably”, but added that any move to exclude it from freeports would simply put “even more jobs at risk”.

The proposed £2bn Solent Freeport scheme, backed by Mr Sunak last year, has potential to create more than 25,000 jobs for the region. It would create a special economic zone where companies would benefit from lower taxes and reduced red tape. The £4.5bn Thames Freeport is intended to create more than 21,000 jobs.

Separately Mr Shapps has also warned P&O’s ferries will not be able to resume sailing until the new crews are cleared by the Maritime and Coastguard Agency. The strait between Dover and Calais is one of the busiest waterways in the world, meaning sailors must be adept at navigating the heavy traffic. 

Mr Shapps told P&O that the inspections, which industry sources say are expected to happen in the coming days, will “ensure that the new crews you have rushed through are sufficiently safe to go to sea.”

It is understood that P&O expects its Dover-Calais services to be up and running again by this weekend.

On Sunday, however, the RMT union said it will seek to oppose any such moves on safety grounds. It is currently seeking legal advice on whether it can challenge the sackings.

Natalie Elphicke, the Tory MP for Dover, said the fastest way to ensure P&O passed its safety checks would be to reinstate the old crews.

“If they want to get the boats up and running by the end of the week, then they should reverse their decision,” she said.

Chancellor hints he’s in favour of restarting fracking in cabinet clash

Rishi Sunak has hinted he is in favour of fracking to help tackle the energy crisis in the latest sign of a Cabinet split over the contentious issue.

The Chancellor claimed that tapping potential reserves of shale oil and gas in Britain was something “we should be exploring” if it could be done safely.

His comments came after Boris Johnson opened the door to lifting the moratorium on fracking. The Prime Minister told Kwasi Kwarteng, the Business Secretary, that it didn’t “make sense” to concrete over shale wells as Britain battles with rocketing energy prices.

It comes as the Cabinet appears divided on whether to reconsider its stance on fracking. Mr Kwarteng has argued it makes more sense to cut reliance on fossil fuels by building renewable power sources such as wind and solar farms, as well as a new generation of nuclear plants. Michael Gove last week backed that position. The Levelling Up Secretary said he was “not convinced” by the case for fracking and that Western countries needed to kick their oil and gas “addiction” as it gave leverage to dominant producers such as Russia.

Ministers are reportedly exploring the creation of a state-owned firm to take stakes in nuclear power projects – a key part of the Government’s plan to reach net zero by 2050 – in a bid to boost flatlined investment. Mr Kwarteng is considering the plans after ministers ruled out Chinese involvement in future plants and alternative investors failed to come forward, according to the Sunday Times.

But Mr Sunak said the Government should also be considering fracking as a potential option to help ease the energy crisis. “If there’s a safe way to do it, then it’s definitely something we should be exploring,” the Chancellor told the Mail on Sunday.

Fracking – formally known as hydraulic fracturing – involves drilling into shale rock and using a high-pressure mix of water, sand and chemicals to release the gas inside.

Cuadrilla was the only company to gain consent to begin fracking, at two sites in Lancashire, before being ordered to stop in 2019 following concerns about earth tremors. It was told by the Oil and Gas Authority to concrete over the wells by June 2022.

Boss Francis Egan has recently warned that just days remained for ministers to change their minds, as otherwise irreversible preparations for the well closures would already have begun. The Telegraph understands that equipment for plugging Cuadrill’s wells in Lancashire is still due to begin arriving on site early this week.

Cuadrill has argued that 37.6 trillion cubic metres of gas is located in the northern Bowland Shale gas formation and that just 10pc of this could meet UK gas needs for 50 years.  

While Britain only imports a small amount of Russian gas, some Tory MPs have in recent weeks claimed that allowing fracking could make the country more independent. It has helped to turn the US into a net gas exporter.

But communities near the wells in Lancashire have raised concerns about earth tremors, while green campaigners say energy companies should be focusing on investment in clean power sources. The Government has maintained it is exploring all options and will set out detailed plans in a forthcoming energy security strategy.