The home secretary has said people could get ID cards using false identities but would be saddled with them for life.
There have already been problems with some biometric technology
Grilled by MPs on plans for a national
ID card scheme, David Blunkett said those fixing themselves with false IDs could lose out on family inheritances.
It was announced last week that 10,000 volunteers would help trial the scheme.
Technical problems have already caused delays to the scheme, the Commons home affairs committee revealed on Tuesday.
'Flood' of applications
The first passports and driving licences using biometric information, such as iris scans or fingerprints, are due to be issued in 2007.
Mr Blunkett told the committee he thought there would be a "flood" of people wanting the new-style documents.
Committee chairman John Denham asked whether it would be possible to obtain an ID card using a false identity.
Mr Blunkett replied: "It would be possible for you to be issued with an ID card
on the identity that, to use your words, you had assumed some years ago.
"But that would be your identity for the rest of your life.
"You will have adopted, by your own actions, an identity that you cannot
Mr Blunkett argued that instead of encouraging people to establish false identities before the scheme began, those using false IDs would either return home or get into their true identity quickly.
"Otherwise, they are going to find themselves in a real mess to establish a real identify of life, including their family and their heritage and any relationship that they have outside the country, including inheritance," he said.
Documents handed to the committee by the UK Passport Service, which is running a trial on biometrics, show the equipment being used had to be withdrawn earlier this year.
There were "a series of hardware, software and ergonomic problems leading to inconsistent enrolment", say the papers.
Mr Blunkett said it was "important to get it right rather than get it quickly" and the process was designed for learning lessons.
But Conservative shadow home secretary David Davis accused Mr Blunkett and fellow Home Office Minister Des Browne of causing more confusion.
"The fact that David Blunkett and Des Browne were not able to provide clear
answers when asked to explain their plans to Parliament is extremely worrying," he said.
"The public already has real concerns about this government's ability to operate
an ID scheme in practice."