The number of active occupational pension scheme members was 9.8 million in 2004, but dropped to 8.8 million by 2007.
ONS says it is likely that the drop would have been even larger if not for a rise in public sector scheme membership.
Occupational pension schemes have decreased in number by nearly 4,000 since 2006.
Revised figures from 2006 released this week indicate that the Government overestimated the number of occupational pension schemes for that year.
Shadow Secretary of State for Work and Pensions Chris Grayling says: “These figures show the long term damage Gordon Brown’s stealth tax raid has done to the UK pensions system. It is little wonder that people no longer trust this Government on pensions.”