The Government is re-evaluating its ID card project as part of a wider review of the Home Office's activities.
Home Secretary John Reid launched the review soon after taking up his post in May, following a series of controversies over the immigration service.
The Home Office confirmed on Tuesday that the ID card project, which will involve a massive database of personal and biometric data, will be included in this review.
"As part of the Home Office review we are ensuring that the sequencing of our plans is coherent and addresses the priorities of British citizens as the Home Secretary has identified. We have always made clear that its introduction would be an incremental process. That remains the position," said a Home Office spokeswoman on Tuesday.
This comes just days after the apparent leaking of internal Home Office emails, in which senior staff appeared to warn that the project, currently estimated by the Government to cost £5.8bn, could be in serious trouble.
Some reports on Tuesday claimed that the planned launch date of 2008 may have to be pushed back as a result of the review, with Computer Weekly reporting that tendering for the programme has been delayed until at least the end of this year.
However, the Home Office denied that the ID card tenders were now on ice. "As far as I know, it's going ahead," said the Home Office spokeswoman.
Opponents of the ID card scheme argue that it will be extremely difficult and expensive to implement, and that the underlying biometric technology is not reliable enough. There are also concerns that the central database of personal and biometric information could be hacked.
The London School of Economics (LSE) warned last year that the total cost of the ID card scheme could reach £20bn.
"The delays to the ID cards scheme announced today come as no surprise to LSE’s Identity Project team: our 300-page report last year warned the Government that its proposals were high risk," said Dr Edgar Whitley, research co-ordinator for the LSE Identity Project, on Tuesday.
"Given repeated statements from Home Office ministers about detailed costings and clear plans for the scheme we are alarmed at the extent of the problems revealed over the past few days."
And following the publication of the leaked emails last Sunday, the No2ID pressure group claimed that the programme "has been built on deception".
"The Government has systematically misled the public, bullied Parliament and anyone who dared to speak against them, and wasted tens of millions already on a scheme that officials now admit is unworkable. Now we discover that the whole thing has been rushed, just to fit Tony Blair's political agenda. The Government's much-hailed "gold standard" of ID is a complete sham," said Phil Booth, No2ID's national co-ordinator, in a statement.