This amounts to a UK savings total shortfall of £132billion, which it is alleged could be much less if workers took up the offer of free expert pension advice.

This “guidance gap” risks financial harm to millions of future pensioners, warns a report from the independent public policy think-tank Social Market Foundation (SMF).

The situation is made worse by more than two-thirds of workers aged 50 to 64 not knowing how much they will need to live off in retirement.

Scott Corfe, SMF research director, said: “There is a serious gap in the provision of advice and guidance around pensions – and that gap leads to financial harm.

“Lacking an accurate understanding of what they will need for the retirement they want means some people will not save enough. Not fully understanding their options on the way they use their pension savings means that some people will not make the best use of that money.”

Just 14 percent of 50 to 64-year-olds use the Government-backed Pension Wise advice service – despite it being free.

Only 20 percent of the same age group see a regulated independent financial adviser about their pension before they retire.

This lack of knowledge and understanding of pensions and savings leaves people at risk of not being prepared enough for retirement or spending their pension pots unwisely, the report warns.

The SMF estimates people approaching retirement age in the UK are nearly a quarter of a million pound short on average of the pot they would need.

The research compared what people think they need against what an independent online calculator suggests they would need.

Only 31 percent with a pension have a broadly accurate idea of the savings needed to deliver a desired income.

This compares to 48 percent who get advice and have a broadly accurate idea of the requirements.

The same is true of 35 percent who have used Pension Wise.

Savings specialists Phoenix Group, a think-tank that sponsored the research, are calling for an overhaul of financial advice rules.

Its chief executive Andy Curran said: “This SMF report identifies how millions of savers could be substantially better off if the gap was closed.”

The report recommends that guidance offered by Pension Wise should be expanded and the minimum age at which people can book an appointment could also be reduced from 50 to 45 or even 40.

Pheonix added that clearer information should also be provided by the Financial Conduct Authority on what constitutes guidance and advice.