The new pension freedoms will be an 'open season' for fraudsters trying to steal people's savings, according to industry experts.
Big changes - which will make it easier to access money in pension pots - are due to happen in one month's time.
But some in the pensions industry are warning that those changes will also encourage criminal activity.
The government is advising people not to take cold calls from fraudsters posing as pension professionals.
Under the existing rules, fraudsters trying to access savings have needed to set up fake pension schemes, before persuading victims to transfer their money.
But from April 6 anyone over 55 will be able to withdraw their pension savings, and put them where they like.
"It's open season for the fraudsters," said Tom McPhail, pensions expert with Hargreaves Lansdown.
"They can target the over 55's, and some unwary investors are going to get drawn into these schemes."
Previous pension fraud has centred on persuading people to "liberate" their pensions before the age of 55.
However criminals have already started to bombard people with phone calls and text messages ahead of the April changes.
Beverley Flavin, from Wolverhampton, was approached by a cold-caller.
She was then persuaded to hand over her £23,000 pension savings to a company which promised to invest it in a start-up venture.
However, the company subsequently went bust - and she does not know whether she will see any of her money back.
"It's devastating for me and my husband," she told the BBC.
"I really wouldn't like other people to be in the same situation I was in, and to have to lose everything."
Some in the industry want to see it made illegal for fraudsters to pose as regulated investment advisers - for example, by saying they are regulated by the Financial Conduct Authority (FCA).
The Association of British Insurers (ABI) also believes that the rules need to get tougher.
"We strongly support action to prevent savers becoming victim to fraudulent pension scams," said Yvonne Braun, director of long term savings policy at the ABI.
"The government, regulators and industry need to work together to combat misuse of the pensions system."
Pensions minister Steve Webb - who himself was cold-called by fraudsters - admits that there are risks involved with making pensions savings easier to access.
"A lot of people will have access to a lot of money come April, and there's a bunch of crooks out there," he said.
He advises people only to take professional advice.
"Pension Wise - our service - is the place to go. Not somebody who cold calls you."
It is already a criminal offence to pose as an adviser from Pension Wise.