Less than half of employees in Britain are now saving into a workplace pension scheme, the lowest proportion since records began in 1997 driven by a fall in membership of final salary schemes, official figures show.

The Office for National Statistics (ONS) said 48 percent of employees were saving into a scheme in 2011, the first time the figure has fallen below 50 percent.

There was a sharp difference between the public sector, where 83 percent of workers were enrolled in their employer's scheme, compared with 33 percent in the private sector.

We've passed an important and worrying landmark, said Darren Philp, Policy Director at the National Association of Pension Funds (NAPF).

Sadly, the fall in people saving into a final salary scheme has not been fully matched by interest in other types of pension.

Workers with final salary schemes, in which payouts are pre-determined using a formula based on salary and duration of employment, declined to 30 percent in 2011 from 46 percent in 1997. This contrasts with 79 percent of public sector workers.

Only 9 percent of private sector employers were contributing to new final salary schemes, down from 34 percent in 1997.

In January, oil company Shell become the last FTSE 100 company to close its final salary scheme to new members.

Pension participation has been getting worse for some time, but we should now be approaching the nadir, John Ball, head of UK Pensions at consultant Towers Watson, said.

Auto-enrolment, under which employers will sign staff up to their corporate pension schemes unless they ask to be excluded, is due to be phased in this year.

The scheme has the potential to create up to 6 million additional savers and boost retirement saving by as much as 12.5 billion pounds ($19.63 billion) a year, research by insurer Standard Life found. ($1 = 0.6369 British pounds)

(Reporting By Anjuli Davies; Editing by Erica Billingham)