In the past three years, 9% of respondents said they have been approached about their pension funds by people they now believe to be scammers.
Half of those approached did not report their concerns because they did not know how to or were unaware of who they could report the scammers to.
Data from Action Fraud, the UK’s national fraud and cybercrime reporting service, shows 991 cases have been reported in the past three years, involving losses of more than £22.7m ($30.8m, €25.7m).
Nearly half of respondents said the approaches involved offers to unlock pension funds or access money early, while slightly fewer said they involved transferring pensions.
About 28% of those targeted by suspected fraudsters were offered alternative investments, such as wine, and 20% were offered overseas investments.
Cryptocurrencies were promoted to 13% of respondents. Around 6% believe they have been victims of fraud.
Prudential’s retirement income expert Vince Smith-Hughes said: “Pension freedoms, though enormously popular with consumers, have created a potentially lucrative opportunity for fraudsters and people need to be vigilant to safeguard their hard-earned retirement savings.
“If it sounds too good to be true then it usually is and people should be sceptical of investments that are offering unusually high rates of return or which invest in unorthodox products which may be difficult to understand.
“If in any doubt, seeking independent advice from regulated professional advisers will help ensure they won’t get caught out.”
Retirement savers can report suspected frauds to Action Fraud and more advice is available from the Pensions Advisory Service.
The survey was conducted by Consumer Intelligence on behalf of Prudential in February 2018 among 1,000 UK adults, working and retired, aged over 55.