Workers could be forced out of final salary pension schemes as 25 firms plan to close them to existing members, the National Association of Pensions Funds said.
An NAPF survey found that a quarter of members who responded said they would stop current contributors saving into the schemes in the next five years.
The majority of the 8,000-plus existing final salary schemes are already closed to new members but if the plans are shut down, savers will be forced put their money into riskier, stock-market linked schemes.
Payments they have already made will be protected, but they will lose the guarantee of a payout to match their salary.
Rentokil is among a small number of firms which have already closed final salary schemes to existing members.
The full findings of the report, revealed on the BBC's News at Ten on Thursday, will be published on Monday.
Investments expert Ros Altman told the BBC News at Ten: "This is the death knell for the final salary pension scheme. Employers cannot afford to fund this long-term commitment any more."
Howard Neville, who had his final salary pension scheme transferred to a stock-market linked investment, told the BBC: "It has made me absolutely sick with worry. And to be perfectly honest I feel like I've been a bit of a mug."
