A leaked draft report from the Audit Commission says: “There is a potential for a black market to develop as parents who don’t want their children to be in pre-school education will still be entitled to a voucher . . . The scheme will need powerful procedures [to prevent] fraud.”

The draft report on nursery education has been postponed until next month, but was leaked to BBC2‘s First Sight, due to be shown last night, which quotes Buckinghamshire councillor Peter Mullins.

Mr Mullins, who defied the party line and stopped the Conservative-controlled council from taking part in the nursery voucher pilot, said: “We can see fraud manifest itself in a whole series of different ways. We can see fraudulent application, we can see people moving addresses . . . we can then see some schools putting vouchers in for pupils who don’t really exist and so on. There are also, presumably counterfeiting issues.”

Colin Douglas, press officer for the Audit Commission, said: “In any major scheme the possibility of fraud is an issue which needs to be taken into account. It is not a criticism of the scheme itself. It is alerting people that this is an issue which will be crucial to its effective implementation. ”

A Department for Education and Employment spokesman promised rigorous anti-fraud measures, with vouchers only being issued to parents on a national database. Otherwise, parents would have to supply supporting documents.