It is the largest-ever closure plan by the company and will radically change the face of the bank, according to Unite.
Shipbuilding Policy Unchanged: MoD
The Ministry of Defence has insisted it has no plans to change the policy of only building warships in the UK, despite reports that the head of the Royal Navy has suggested work could be done abroad.
First Sea Lord Admiral Sir George Zambellas is reported to have said he had not "necessarily said that that's the British industry'' that must deliver on issues of affordability.
Defence contracts were a key issue in the run-up to September's independence referendum, with pro-union politicians claiming Scotland's shipbuilding industry would automatically be precluded from MoD deals in future if it left the UK.
SNP defence spokesman Angus Robertson said the First Sea Lord's comments "puts the lie to yet another Project Fear scare story rolled out during the referendum''.
Mr Robertson said: "Time after time we were told by the No campaign that warships could only be built in the UK. The best place to build these frigates is on the Clyde and everybody knows that.
"It would be a serious breach of trust if this is now being reconsidered - Scotland needs and deserves this work.''
Industry publication Defense News reported that the First Sea Lord, who is the Royal Navy's professional head, had raised the prospect of contracts being awarded to other countries.
It reported him as stating: "The acquisition process looks for a solution... to be able to give us what we need. The affordability question that comes from that depends on the best that industry can deliver. You'll notice, I haven't necessarily said that that's the British industry, because the decision has not been made as to exactly what that solution to the requirement will be, and we wait to see what comes of it.''
That was refuted by a Ministry of Defence (MoD) spokesman, who stated: "As the Defence Secretary has made very clear, complex UK warships are only built in UK shipyards and we have no plans to change this. And while this contract has not yet been awarded, we have also been clear that from 2015 the Clyde will be the UK's only shipyard that builds complex warships.''
Scottish Secretary Alistair Carmichael said: "Our position is clear. The UK builds its warships within the UK, and always has done.
"The MoD has today said it does not anticipate any change to this policy in respect of the Type 26 Global Combat Ship. The only damaging change for shipbuilding in Scotland would have come from independence. We saw, at every point in the referendum, that the Scottish Government had absolutely no answers on its future. We know the expertise and skills in Scotland are world-class and I am confident they will win through.''
The SNP claims a "Hard Brexit" will cost 80,000 jobs in Scotland.
A bullet has been recovered from a tree where a man was shot near a primary school.
Scotland's jobless total rose by 11,000 in the three months to November.
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