DEFENCE chiefs have attempted to reassure ­Scottish shipbuilders after the head of the Royal Navy appeared to suggest a £4 bil­lion contract for new warships may go abroad instead of to the Clyde.

The order for Type 26 frigates is considered crucial to shipbuilding in Scotland, and the future of the Clyde shipyards was a key part of the referendum campaign.

Last night sources close to Defence Secretary Michael Fallon were unequivocal the contract would not go abroad, saying: "UK warships are only built in UK yards. There will be no change in that."

A Ministry of Defence spokesman added that from 2015 the Clyde would be the UK's "only shipyard that builds complex warships".

Scottish Secretary Alistair Carmichael added: "The UK builds its warships within the UK, and always has done … The only damaging change for shipbuilding in Scotland would have come from independence."

But Angus Robertson, the SNP's defence spokesman, said comments by the First Sea Lord, Sir George Michael Zambellas, showed that voters had been lied to ahead of the referendum.

Labour's shadow defence minister Alison Seabeck also called on Mr Fallon to clarify the remarks by the head of the navy.

In an interview, Admiral Zambellas said the acquisition process for the frigates "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".

He added : "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."