The London School of Economics (LSE) has estimated that the government's controversial identity card scheme will cost more than twice as much as initially thought.
The six-month study stated that the government's prediction that consumers would pay £93 was "overly optimistic".
The report warned that costs could go as high as £230 per person, and that the whole scheme could cost £19.2bn. It also said that potential technical problems could drive the costs even higher.
"The report concludes that the establishment of a secure national identity system has the potential to create significant, although limited, benefits for society," said the LSE.
"However, the proposals currently being considered by Parliament are neither safe nor appropriate.
"There was an overwhelming view expressed by stakeholders involved in this report that the proposals are too complex, technically unsafe, overly prescriptive and lack a foundation of public trust and confidence."
The report highlights deep concerns about the technology behind the cards, calling it "untested and unreliable". Of particular concern is the use of biometrics, which has never been used on such a scale.
As for the database behind the system, the report found that this would have no effect on identity theft, and could even make the problem worse by collecting all valuable data in one place.
It added that the proposed National Identity Register "may pose a far larger risk to the safety and security of UK citizens than any of the problems it is intended to address".
Richard Thomas, the UK's Information Commissioner, said: "I welcome the report commissioned and undertaken by the LSE as a valuable contribution to an issue which engages significant data protection and privacy concerns.
"I have expressed my unease that the current proposal to establish a national identification system is founded on an extensive central register of personal information controlled by government, and is disproportionate to the stated objectives behind the introduction of ID cards.
"It raises substantial data protection concerns about the extent of the information recorded about an individual when the ID card is used in their day-to-day lives, and sparks fears about the potential for wider use/access to this information in the future."
Privacy groups have been waging a campaign against the cards with an online petition and the creation of a fighting fund.
Tony Benn, three sitting MPs and the head of civil rights pressure group Liberty will be holding a public meeting to coincide with the second reading of the bill.
Doug Jewell, campaign co-ordinator for Liberty, said: "The government is saying that it cannot release all its cost figures for commercial confidentiality reasons; it's a nice thing to say.
"The government has a track record on large-scale IT projects; they cost a lot more than was estimated and are a lot more complicated. There seems no reason why this project should buck that trend."
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