Britain's cutting-edge £1billion warships are breaking down in the Persian Gulf because they are not designed for the heat.

Contractors claim the Ministry of Defence did not tell them the 8,000-ton Type 45 Destroyers would be spending a long time in warm waters.

As a result, the six warships have an engine which keeps cutting out in the middle of the sea, leaving servicemen stranded for hours in total darkness.

Britain six Type-45 Destroyers, including HMS Daring (file picture), and all six need to have back up diesel generators fitted as back ups in case of main engine failure in warm water

The revelation yesterday raised fears that Britain’s key naval assets – designed to shield the rest of the fleet from air or missile attacks – have become ‘sitting ducks’.

There were also warnings that troops could be killed as the ships are deployed near combat zones in the Middle East.

Four of the guided-missile ships are currently at sea, with one outside Europe and the others in UK waters. Described as the backbone of the Royal Navy, they are fitted with a pioneering new system designed to cut costs and be more fuel efficient.

Two turbines on each ship, made by Rolls-Royce, have intercooler units which recover heat from the exhaust and recycle it into the engine. But a design flaw means the turbines slow down in warm waters and the engine cannot generate enough power. The system does not recognise this and keeps demanding more power, causing the ship’s generators to ‘trip out’ – leading to total electrical failure.

The warships work in the North Sea because the engine can generate more power in colder temperatures.

They are now set to undergo a refit costing tens of millions of pounds to put in extra diesel generators. This could involve cutting a giant hole in the side of each ship.

MPs yesterday said they were ‘stunned’ by the fault, which they feared had put British troops at risk. Their anger came as two former heads of the Navy claimed the service had run out of money – and that the costs associated with fixing the Destroyers had delayed another warship programme.

The warships work in the North Sea because the engine can generate more power in colder temperatures. They are now set to undergo a refit costing tens of millions of pounds to put in extra diesel generators. This could involve cutting a giant hole in the side of each ship

Admiral Lord West said putting off replacing the Navy’s ageing Frigates was ‘bloody dangerous’. And he warned that further delays would leave the UK fleet ‘grossly inadequate’ for the tasks it faces.

Cross-party MPs lambasted the firms responsible for the Type 45 Destroyers’ design flaw.

Tomas Leahy of Rolls-Royce, which made the engine, said his company had been given a specification by the MoD detailing its requirements.

He told the defence select committee: ‘Are the conditions experienced in the Gulf in line with that specification? No, they’re not. So the equipment is having to operate in far more arduous conditions than were initially required.’

He described how the heat had led to total electrical failure and the ships ‘plunging into darkness’.

Tory MP Julian Lewis, the committee chairman, asked: ‘How many years do you think that the Royal Navy has had a naval presence in the Gulf, would it be measured in decades, scores of years, a century?

‘Why should it come as such a surprise that there would be these sorts of climatic demands and obstacles?’

John Hudson of BAE Systems, which built the Type 45, replied: ‘I think the Navy have operated in the Gulf for many, many years and we are aware of that.

‘I think the operating profile that was considered at the time was there would not be repeated and continuous operations in the Gulf ... and therefore it wasn’t designed explicitly and uniquely for operations in the Gulf.’

SNP MP Douglas Chapman responded: ‘I’m absolutely stunned, to have a billion-pound asset that you’re putting into a warzone and we don’t know if these people will go in there and come back alive because there might be a problem with the power system. I’m stunned.’

Lord West, pictured at today's defence committee, said it was a 'bad position' for the Navy to be in to have to refit the six Type-45 Destroyers

He added: ‘We’ve got a battle-ready ship in the Gulf, it is sitting there as a sitting duck basically because if you have a lack of power ... that’s an amazing level of risk that the MoD were prepared to accept.’

In an excoriating attack, Labour MP Madeleine Moon added: ‘What I find difficult is that here we have a critical defence capability that basically doesn’t work, is not reliable, and places the country and the people who serve at risk and none of you seem to be saying, “I’m really sorry about this”.’

But Dr Andrew Tyler of Northrop Grumman, which provided one of the systems for the ships, said: ‘It is very difficult to fully simulate a lifetime’s worth of conditions. There’s always a risk of some discovery once a system enters service.’ Also at the inquiry were former Navy bosses Lord West and Sir Mark Stanhope, who raised serious concerns about the state of the service’s 19 main warships.

Along with the six Type 45 Destroyers, there are expected to be 13 anti-submarine Type 26 Frigates being brought into service to replace older vessels – although there are fears this will be reduced to eight.

Referring to the Type 45 problems, Lord West said: ‘Our 19 Destroyers and Frigates are effectively 13 and if there was a major war we might well have air defence units that aren’t able to do air defence.

‘I think it is a terrible error that our nation is making in allowing this to happen.’

Sir Mark added: ‘It needs to be resolved ... we’ve got to do this quickly because of the risks involved in total power failures at the wrong time.’