Giving a keynote speech in Glasgow, Johann Lamont said if Westminster vetoed Alex Salmond’s currency union plans interest rates would shoot up, The Scotsman reported.

Lamont said: “We are still waiting for the First Minister to tell us the basic of what currency we would have in an independent Scotland. But whether it is the groat, the bawbee or a currency union with the Armenian dram, what we can be assured of is that our interest rates would be higher.”

Analysts have predicted that rates in an independent Scotland would be 1 to 2% higher than in the rest of the UK.

Lamont said that a 2% rise on an £80,000 mortgage would result in an increase of £1,600 more for borrowers to pay ‘for the privilege of living in Salmond’s Scotland’.

Salmond has threatened to default on an independent Scotland’s share of UK debt if Westminister blocks currency union plans, which all three of the main political parties have pledged to do.

Lamont said defaulting on the debt would cause rates to rise even higher than the 2% differential which has been predicted.

The referendum on Scottish independence will be held on 18 September.