THE government of an ­independent Scotland would have to spend more money to provide state pensions to a growing number of pensioners, the professional body of financial risk assessors has warned.

The Institute and Faculty of Actuaries(IFoA) also called on the SNP administration to provide "more detail" on how additional costs and risks would be managed with the establishment of a separate pensions system, should there be a Yes vote in September.

The views were expressed on the day the UK Government published its paper on pensions, welfare and independence, claiming SNP pension pledges and Scotland's ageing population would add an extra £410 a year per working-age person over the next 20 years. When other social policies are included this rises to £450, the Whitehall paper says.

Nicola Sturgeon, the Deputy First Minister, has dismissed the Coalition claims as scaremongering, insisting welfare spending and pensions would be "more affordable" in Scotland than the UK because they accounted for a smaller proportion of tax revenues and national income.

In his response to the Whitehall analysis, Martin Potter, head of the IFoA's Scottish Board, noted that actuaries, as experts in analysing longevity and costing long-term pension promises, were at the ­forefront of the changing pensions landscape.

Pointing out that pension costs were paid for by working-age people, he said: "In Scotland the number of working-age people is projected to increase more slowly than the rest of the UK. This means it is likely pensions for the growing pensioner population will require a greater proportion of government expenditure in Scotland in decades to come."

Pro-UK politicians seized on his words, with Labour's Gregg McClymont saying Scotland's actuaries had now joined its accountants to warn pensions were at risk from a threatened break-up of Britain.

He said: "The Nationalists tell us that everything will be fine on pensions but can't even tell us how they would be paid for. "

Meanwhile, Ms Sturgeon hit out at Alistair Carmichael after the Scottish Secretary said the UK government's welfare system was "fantastic" as it provided "support for some of the most vulnerable people in our communities".

She said: "There has been a 400% increase in the number of people forced to use food banks ... as a result of callous Tory/LibDem cuts."