The SNP have hit out at plans to tell older people how long they can expect to live to prevent them blowing their pensions on fast cars.

Sending the forecasts to retirees would cause distress and be insensitive, one of the party's MSPs said.

Coalition ministers have said the letters could be sent out as early as next year.

The proposal follows ­criticism over planned pensions reforms that would mean no-one was forced to buy an annuity.

Opponents warn the changes could lead pensioners to spend all their cash instead of saving for old age.

While they reject that argument, Tory-Lib Dem ministers do believe many older people underestimate how long they will live.

An estimate of when they might die, based on gender and where they live, could allow older people to plan ahead but also allow them to spend any savings.

But SNP MSP Annabelle Ewing, who sits on Holyrood's Welfare Reform Committee, said: "Writing to individual people with a prediction of their life expectancy is insensitive and likely only to cause distress."

A leading pensions expert warned retirees risk being misled by the estimates.

Ros Altmann, an independent pensions expert and a former Downing Street adviser, said the information would be "not terribly helpful" unless regularly revised.

"By the time five or 10 years have gone by, things can change by a big amount for lots of people," she said.

The proposed guidance could be rolled out as early as April next year.

Last month, LibDem pensions minister Steve Webb was criticised for saying he was "relaxed" about pensioners using their money to buy a Lamborghini.