The SNP is calling for clarification on the future of the contract to build frigates on the River Clyde

Union leaders last night accused the SNP government of failing to understand shipbuilding after the party critcised David Cameron’s defence review.

The prime minister confirmed yesterday that the Trident nuclear deterrent would be renewed, at a price which has risen from £25 billion to £31 billion.

Mr Cameron also said eight Type 26 combat vessels would be built on the Clyde, a cut from the planned 13 frigates, but there would be a subsequent announcement on more vessels.

Brendan O’Hara, the SNP’s defence spokesman, had said there was “much in this defence review that is deeply troubling and the workforce at the shipyards on the Clyde will feel betrayed by the huge cut in the number of Type 26s to be ordered”.

He added: “It