Men aged in their 50s are the most likely victims of fraudsters who target people's long-term pension savings.
More than £30m has been lost since 2017 to pension fraud, according to Action Fraud, as unauthorised "advisers" tout unrealistic investments.
Now financial regulators are stepping up warnings for savers to take care and take their time over decisions.
Many people have used lockdown to review their finances, hoping for better returns.
The scam starts with an unexpected call, text, social media approach or email offering a free pension review, or a way to make attractive returns on pension savings.
But the money may be simply stolen or transferred into a high-risk scheme completely inappropriate for retirement savings.
Many offer eye-catching returns or high-rolling investments in hotels or green energy schemes that never materialise, or instead lead to losses.
Often, extra pressure is put on potential victims who are told the offer is time-limited.
In January last year, the government introduced a ban on unsolicited calls offering pension "deals" of this kind. Any firm found flouting the rules faces a fine of up to £500,000, but experts suggest fraudsters may ignore the ban.
Men in their 50s tend to be targeted as they may be keen to extend their investments before retirement, and may have fairly large pension pots. However, fraudsters still cold-call all ages.
Fraudsters target pension pots of any size, with reported losses usually range from £1,000 to £500,000, the Financial Conduct Authority said, although there have been rare cases of losses topping £1m.
One of those who lost money was Viv, aged 57.
"It was a call from a man who seemed very decent and respectable. He seemed knowledgeable and trustworthy. I didn't know much about how pension transfers worked then and he sounded convincing," she said.
She ended up losing £200,000.
"Looking back, there was no cooling off period for me, no warning - all I had was a letter, which I put down on the kitchen table and forgot about. I had a lot of other worries at the time, including looking after my poorly mother. Now I am really aware of the warning signs about scams," she said.
Tips for avoiding scams
- Reject unexpected pension offers whether made online, on social media or over the phone
- Check who you're dealing with before changing your pension arrangements. Check the FCA Register or call the FCA contact centre on 0800 111 6768 to see if the firm you are dealing with is authorised by the FCA
- Don't be rushed or pressured into making any decision about your pension
- Consider getting impartial information and advice
Sarah Coles, from investment platform Hargreaves Lansdown, said: "One of the reasons we can be taken down by scammers is that we know so little about what's in our pension. It makes it far easier for a criminal to persuade you they know best, and get you to turnover decades of savings to them.
"Our research shows only a third of people know how much is in their pension pot, and less than a third know it's currently invested in the stock market."