Signing up can often be disastrous. If someone has a pension pot of £20,000, schemes may offer them access to half of that.
The scheme will take a commission of around £4,000 - 20% - leaving the victim £6,000 in their pension fund.
That is often invested in offshore vehicles and might never be seen again.
The individual will also be obliged to pay tax of between 55% and 70% on the money released.
The Pensions Regulator is about to launch a publicity drive to warn people of the dangers.
Bill Galvin said it is taking strong action against rogue firms.
"We have shut down over the last 18 months a number of vehicles which have been used for 'pension liberation' schemes, we have installed independent trustees," he said.