The government has doubled the anticipated cost to individuals of obtaining an ID card by adding a charge for collecting biometrics through the private sector.

Plans outlined by home secretary Jacqui Smith provide for high street chains such as WHSmiths or the Post Office to collect facial scans, fingerprints and eventually retinal scans for an anticipated fee of about £29 in addition to the £30 charge for issuing the card.

The proposals have been buried in documents made available by the Home Office, but this is the first time that a senior minister has pointed them out in a major speech and guidance has been available on cost.

Smith gave the details in a speech to the Social Market Foundation in which she claimed that projected costs are falling and that an estimated £1bn will be wiped from the current estimate of £5.4bn over the next 10 years by next May, when the process of tendering contracts is due to be completed.

But her figures contrasted with the rolling 10-year estimated cost issued the same day by the Identity and Passport Service showing that projected costs have risen £53m over the past six months to a total of just over £5.1bn in set-up and running costs for domestic and foreign cards for the next decade.

Shadow Tory home secretary Dominic Grieve suggested that the extra biometric collection charge is "particularly outrageous given the current economic crisis ".

"The home secretary should stop kidding herself, admit this project is dead and devote her energies to carrying out her primary responsibility which is ensuring the safety of the citizens of this country," he said.

Liberal Democrat spokesman Chris Huhne described the newly revealed "hidden" charge as "incredible cheek".

The Home Office denied reports that plans to issue the card early to 200,000 airside airport workers next October in an 18-month trial have been scaled back because of the threat of industrial difficulties.

But the department confirmed that it is now to be limited to staff at Manchester and City of London airports, with the sweetener of the cards being issued free of charge and with a £500,000 Home Office payment to cover airport costs.

Cards are being issued to foreigners from the end of this month and will be available earlier than expected to a handful of public volunteers by the end of 2009.

Officials claimed that the rollout had always been planned for the second half of 2009 and is "still on track".

Smith said that what she termed the "market" for providing biometrics would be worth £200m.