Ministers do not know how many people are moving back into the state pension system, a disclosure that has been described as "extraordinary" by Liberal Democrat pensions spokesman Steve Webb.

Forum Response: Office of the Pensions Advisory Service

Malcolm McLean, chief executive of OPAS, told ePolitix.com: "This question of whether an individual should opt to be in or out of the state second pension scheme (formerly known as SERPS) is becoming a real issue which the government needs to take note of.

"My impression based on the sorts of calls we are taking on this subject from the public is that many people are being persuaded to move back in to the state scheme because they have read or heard somewhere that they would be better off doing so.

"It must be stressed that this is an individual decision and depends on your personal position - for example how old you are, what sort of personal plan you have and how its doing, why you contracted out in the first place, your level of earnings, your attitude to risk and so on. It would be quite wrong to say that everyone who is currently contracted out should now contract back in - as is the impression that seems to be gaining momentum.

"Ideally anyone who is contemplating a change should sit down with a financial adviser and fully consider their options before finally deciding what to do. This is unfortunately easier said than done. Many financial advisers are reluctant to take on this sort of work which is not financially rewarding to them and people therefore are often left in the dark as to what is the best thing for them to do.

"Although as an organisation, we in the Pensions Advisory Service cannot give definitive financial advice we are willing to explain the issues and factors in general terms that we believe people should take into account before reaching their own decision as to how to proceed.

"The OPAS telephone Helpline number is 0845 6012923."

Forum Response: Help the Aged

Richard Wilson, incomes policy officer at Help the Aged, told ePolitix.com: "This disclosure by the government highlights another gaping hole in the government's data on pensions. Not only do they not know how much we are saving in private pensions, but now it seems they do not even know how much we are saving through state pensions.

"No wonder the government's pensions green paper was widely criticised for being not up to the job of stemming the crisis in pensions, indeed, for failing to recognise that there is a crisis.

"Ministers need to quickly address this shambles, firstly by finding out what the real situation is now, not what it was three years ago. Only then can they develop policies that will protect future generations of pensioners from poverty."