His comments come as the government prepares to formally publish the White Paper setting up the National Pensions Saving Scheme.

Savers under the scheme subjected to means-testing, which could impact on a third of the population, could end up no better off than those who do not save at all, Lord Oakeshott warned.

David Laws, Lib Dem work and pensions spokesman in the Commons, said means-testing benefits “will lead to many people losing up to 85 pence of every pound that they save”.

The heads of pensions strategy at Scottish Life, Steve Bee, is leading a campaign to urge the government to clarify the impact of means-testing.

Mr Bee told the Telegraph: “Means-testing is the elephant in the room which the government has so far tried to pretend is not there.”

His campaign aims to get clearer messages from the government so that savers can make more informed decisions about opting in – or out – of the scheme.

For more information about personal pensions, click here.

© Adfero Ltd