The government has agreed to a cut-price, £30 standalone national ID card for the elderly and those on low incomes who do not have a passport.
The cut-price card will be available to those who choose not to hold a passport but will be valid as a travel document within the European Union.
Home Secretary Charles Clarke said the subsidised, standalone 10-year ID card fits in with Home Office spending plans and current financial estimates of the ID cards scheme.
But the government still refuses to disclose how much it intends to charge the majority of the population for the combined biometric passport and ID card package that will be introduced from 2008.
The current Home Office "best estimate" for the average unit cost of producing the combined passport and ID card package is £93, but the London School of Economics claims the unit cost will be closer to £300.
In a written answer to a parliamentary question, Clarke also revealed the Home Office commissioned accountancy firm KPMG to carry out a review of the ID cards costing methodology.
KPMG has concluded the costing is "robust and appropriate" but recommended improvements to the sensitivity analysis and revisiting some of the cost assumptions. The Home Office says it plans to publish an executive summary of the KPMG report "in due course".
In a rallying call, before next Tuesday's crucial House of Commons vote on the Identity Cards Bill, Clarke said: "In future, the recording of biometrics, such as fingerprints, iris patterns or facial image means that we will have a much stronger way of linking identity to the person. A national ID card will be a robust, secure way to establish that identities are real, not fabricated."
The Home Office has already admitted to spending more than £20m on the ID card scheme before the bill has even been put on the Statute Book.