The Policy Exchange also claimed that the Government lacked ambition in its pensions reforms, with serial changes to the state pension system having no real impact.

It warned that over-regulation, rising life expectancy and higher costs had combined to produce a perfect storm in pensions.

The group said Britain had once had an enviable reputation for high-quality pensions, but occupational schemes had been in decline for years.

It said just 15% of private sector employees were now members of defined benefit schemes, such as final salary pensions, and just 4% of people belonged to schemes that were still open to new members.

Less than one in four UK workers now have a private pension as their main additional source of retirement income to the basic state pension, down from 39% in 1991/1992.

The research added that group personal pensions, had contribution levels which were around a third of those paid into final salary schemes, at just 9.9%, compared with 28.7% for final salary pensions.

At the same time it said the state pension system, which it claimed was already the most complicated in the world, was set to become even more complex in future.

The Policy Exchange also warned that public sector pensions, which are generally still the more generous final salary schemes, were growing in size and cost, with the annual charge to the taxpayer set to soar by 33% by the 2030s from 1.5% of GDP to more than 2%.

Principle author of the report Nicholas Hillman said: "Some of the Government's reforms offer an improvement on the status quo. But they will make little difference to pensioners' incomes overall. There is next to nothing to encourage employers to provide generous pensions and personal accounts are a disaster waiting to happen because the implementation risks are so enormous."