The move will not help workers who have already lost their pensions

The change in the rules means that if a firm goes under without enough money in its pension fund, workers who have not yet taken their pension will benefit.

Previously they have lost out while existing pensioners have been looked after and money set aside to increase their pensions in line with inflation.

The move will not help those workers who have already lost their pensions.

Failed schemes

But the cash previously set aside to increase pensions in line with inflation will instead go to those who have not yet claimed.

They have historically have been left with very little in the pot, BBC personal finance correspondent Richard Scott said.

The move will mean people who are already drawing company pensions will become worse off as a result, he said.

And the fund will not offer protection to an estimated 60,000 people who are already at risk of losing all or part of their retirement savings because of a failed company scheme.

Employers' liability

The new measures are designed to help workers before the pension protection fund comes in next year under the Pensions Bill.

Employers operating pension schemes will have to pay into the fund, which will compensate workers if their company pension scheme is wound up.

In addition, a pension regulator will be set up to ensure new rules are followed and to combat fraud.