Last year saw a fall to 8.7 million in the number of employees contributing to workplace pension schemes.
The figures were revealed in a report published by the Office for National Statistics (ONS).
According to the ONS survey, nine million people were paying into company pension funds in 2008.
The decline was accounted for in its entirety by private sector retirement savers.
Public sector schemes totalled 5.4 million, a figure that held steady in both years.
However, there was a drop of 0.3 million in the number of employees participating in private sector schemes, down from 3.6 million in 2008 to 3.3 million in 2009.
Membership of defined benefit schemes – final salary funds – showed the most marked decline.
In 2009, defined benefit schemes shed some 0.2 million active members, while defined contribution schemes remained at a membership of 1 million.
Barely a half (44 per cent) of defined benefit schemes were still open to new members.
There was a sharp contrast in the level of contributions between defined benefit schemes and defined contribution schemes.
In the private sector, open defined contribution schemes had total contributions worth 9.3 per cent of pay.
On the other hand, defined benefit schemes, where they were still open, enjoyed total contributions on average of 20.3 per cent of salaries.
Again on average, employers contributed 14.9 per cent of salaries to open defined benefit schemes, but only 6.4 per cent to open defined contribution schemes.
The divide was also noticeable in staff contributions: whereas employees paid, on average, 5.4 per cent of earnings to defined benefit schemes, the level fell to only 3 per cent for defined contribution schemes.
Hazel Mitchell, editor of the ONS report, said: “Five years ago the number of active members of open DB schemes in the private sector was around double that of open DC schemes.
“Since then, active membership of open DB schemes has fallen to similar levels as for DC schemes.”