Scotland could lose key contracts to build new Royal Navy ships if it votes in favour of independence in next year's referendum, Cabinet ministers forecast today.
Their warning came after the Government announced it was protecting shipbuilding jobs in Glasgow while scrapping them in Portsmouth.
The decision left David Cameron facing accusations from MPs of all parties of being motivated by shoring up the "no" vote in Scotland at the expense of jobs in England.
But Philip Hammond, the Defence Secretary, and Alistair Carmichael, the Scottish Secretary, signalled that today's announcement could be reversed if the Scots opted to leave the United Kingdom.
Mr Hammond said: "The UK has always built complex warships in the United Kingdom so that it has sovereign control over the operation of those contracts."
Mr Carmichael told the Commons it would be "difficult to see how the work would go to Scotland" if it was independent.
MPs from the south of England reacted furiously after the defence giant BAE Systems said shipbuilding would end at Portsmouth in mid-2014 with the loss of 940 skilled jobs.
It will continue in two BAE shipyards on the Clyde, where three new Type 26 Royal Navy warships are to be built, although the Scottish yards will also suffer some redundancies.
The decision was taken against the backdrop of polls indicating a comfortable majority in Scotland among opponents of independence.
There were suspicions that ministers feared a move to end shipbuilding on the Clyde would have played into the hands of Scottish First Minister Alex Salmond.
Mr Cameron's official spokesman refused to deny the independence referendum had been a factor in safeguarding Scottish shipbuilding. He argued the decision had been taken in the "national interest".
Mike Hancock, the independent MP for Portsmouth South, said the move had "undoubtedly" had been affected by the impending referendum.
"I think the people of Portsmouth are going to be paying a very heavy price for, I think, a slightly cynical manoeuvre and I'm disappointed at that," he said.
The former Labour cabinet minister John Denham, a Southampton MP, said: "Many on the south coast feel they have been sold down the river by a government whose interest and attention has been elsewhere."
The Conservative MP for Gosport, Caroline Dinenage, whose constituency is home to many dockyard workers, protested that jobs in Hampshire had been "sacrificed" to Scotland.
The announcement also left the Government struggling to explain what might happen to naval contracts awarded to the Clyde if Scots vote on September 18 to leave the United Kingdom.
The Prime Minister's spokesman insisted he was confident that would not happen and would not be drawn on whether shipbuilding would return to Portsmouth in the event of a "yes" vote.
But the warning by Mr Carmichael that Glasgow could lose the naval contract was attacked as "absurd" by the Scottish National Party.
Angus Robertson, its defence spokesman, said: "It is plain daft for a UK Government minister to say it would be difficult to have ships built in Scotland just because we exercise our democratic right to vote Yes, when the Ministry of Defence has procured vessels from Korea."
Vernon Coaker, the shadow Defence Secretary, said: "We need clarity from the Government about what safeguards are in place to meet all eventualities after next year's referendum."
In a statement to MPs, Mr Hammond said every effort would be made to redeploy workers, and compulsory redundancies would be kept to a minimum.
He said more than £100m will be invested in Portsmouth's naval base so it can accommodate new warships in its maintenance role. But he acknowledged: "The loss of a shipmaking capability will be a harsh blow to Portsmouth."
BAE said it remained committed to continued investment in Portsmouth as the centre of its maritime services and high-end naval equipment and combat systems businesses, adding it was being hit by a "significant" reduction in workload following the peak of activity on the aircraft carrier programme.
Gary Cook, regional organiser of the GMB, said every single job loss in Portsmouth will be opposed, adding: "The contempt shown to the workers by BAE and the Tory coalition by leaking stories to the media before the affected employees were informed, is nothing short of a stab in the back and a national disgrace.
"If the Government wants their second aircraft carrier, a large proportion of which still sits in the build facility at Portsmouth, they're going to need to talk to us about how we preserve jobs and protect the livelihoods of hundreds of people."
he announcement was attacked as a politically motivated "act of lunacy" by Portsmouth Conservative councillor Alistair Thompson, who said: "This is devastating for the workers and their families but also for all those people involved in the supply chain that keeps the dockyard working.
"Many of those who I represent as a councillor are hugely concerned that this decision has been taken for political reasons because of the referendum in Scotland next year.