Blunkett said last weekend that he was giving "a fairly high priority" to ID card plans, and added: "I think a voluntary card, under the present circumstances, would not be a great deal of help".
A compulsory identity card system would be a complex IT project, involving both the issue of cards and the creation of a database holding information on every UK citizen and any non-UK residents arriving in the country.
The government has a number of initiatives underway that could form the basis of an identity card scheme. But Tony Lock, senior analyst Bloor Research, told CW360: "This is not going to be a quick fix. It needs to be delivered on time and it needs to be safe."
Lock estimated that it could take at least six months for the government to define and specify a national identity card system. "The government needs to determine the scope of any national identity card to avoid making expensive changes once the project is underway," he said.
Peter Sommer, senior fellow at the Computer Security Research Centre at the London School of Economics, told CW360: "Technically, a national identity card system is not difficult, as records of people are kept for National Insurance."
However, any database would have to contain personal details for over 60 million citizens and could hold biometric data such as a fingerprint and a photograph for facial recognition.
"There would need to be very good security to prevent false data from being entered," said Lock.
The government has a bad track record with large-scale IT projects, although it is now devoting considerable efforts to putting things right.
The National Insurance Records computer systems, the Pathway Post Office swipe card system and the Inland Revenue's outsourcing contract with EDS have all seen delays and cost escalations as the complexity of the projects increased.
Various government departments have smartcard projects underway or are considering using smartcards. As far back as 1996, the House of Commons Social Security Committee considered calling for a smartcard encoded with a DNA fingerprint to make the National Insurance system more secure.
Frank Field MP, then chair of the committee, said that such a system could eventually hold medical history and criminal records and become a de facto national identity card.
In July 2000 Alex Allan, the government's first e-envoy, discussed the need for an identity card or number in order to meet targets for putting government services online by 2005.
The Passport Agency is looking at a photocard passport that could lead the way to a smart national identity card. Under the proposal the passport photocard would be based on a pocket-sized version of the digitally encoded page used in the latest versions of paper passports.