The study, by financial provider Key Retirement, showed 28 per cent believe they will never be able to afford to give up work, with one in ten planning on working full-time.
And among those who believe they will have enough saved to retire, there is uncertainty, with 15 per cent admitting they don’t know when they stop working.
In Yorkshire and the Humber, almost three quarters of over 55s still working said they were concerned about running out of money, while 17 per cent said they did not plan to give up work altogether.
Fear of running out of money in retirement is the major reason for continuing to work, with 75 per cent of over-55s who are still in work concerned about the risk of running out of money.
The report’s authors say the “striking” results of the survey paint “a worrying picture of the current state of retirement”.
Dean Mirfin, group director at Key Retirement said: “Of course, many of those planning to work until they drop may be entirely happy about it - Government figures show a steady rise in over-65s who are working.
“But the other side of the coin is that millions are worried about having enough money to survive in retirement and that is a major factor in staying in work. Even those who plan to retire are not entirely certain when they can afford to.”
Last month, the Department of Work and Pensions announced that there are now 1.2 million workers aged over 65, compared with 874,000 in December 2011.
Since the Government abolished the default retirement age in October 2011, nearly a quarter of a million more people over 65 have stayed in work. It is also working to help people over 50 stay in work, retrain, or get back to work.
Pensions Minister Steve Webb said people “should have the right to work as long as they feel necessary to create the future they want”.
“The irony is that while myths are peddled about people having to work ‘until they drop’, in reality many older workers are forced out of the labour market long before they feel ready to retire – that’s the real problem we need to address,” he said.
“This is in the context of a wider programme of radical pension reform which is delivering a fairer state pension, getting millions more people into workplace saving schemes, and giving people unprecedented freedom around how to use their pension pot in later life.”
The TUC had long claimed that the Government’s benefits and pension reforms will leave pensioners worse off.
General Secretary Frances O’Grady said: “No-one should be forced to keep working simply because they cannot afford to retire. With the continuing squeeze on wages, money remains tight in many households and people have used up any savings they may have had, and are loading up the credit card just to make ends meet.
“In addition rising house prices mean many families and individuals have huge mortgages to pay off, while others are worried their pension won’t be enough to allow them a decent standard of living into their old age.
“Everyone in work needs a decent pension so they can enjoy their retirement, and although auto-enrolment is helping, employer contribution rates are still too low. Employers need to do more to help staff save for their retirement or many workers will either be working until they drop or living out their twilight years in pensioner poverty.”