The academic whose report on ID cards was branded "technically incompetent" by Charles Clarke has launched a counter attack on ministers.
Mr Davies says he has an alternative ID card scheme
Simon Davies was one of the authors of the London School of Economics paper which suggested the cost of the scheme could reach £19bn.
The home secretary has described the findings as "fabricated".
But Mr Davies said the government's reaction had been "appalling, hypocritical" and "desperate".
The row, which was sparked by the publication of the LSE report last month, is set to reignite as the government's ID Cards Bill begins its committee stages in the House of Commons.
The report claimed that its best case scenario for the cost of the scheme was £10.6bn (about £170 per card and passport).
Its worst case estimate was £19.2bn - more than three times government estimates. Ministers estimate the cost will be £93 a card.
The LSE also identified "ten key uncertainties" over the project, including security concerns, how often would the cards need renewing and how difficult it will be to get people to use the scheme.
However, Mr Clarke dismissed the studies findings, accusing Mr Davies of being "partisan" because his opposition to the cards was well known - and said the whole episode had discredited the LSE's reputation.
In an interview with BBC Radio 4's Today programme, Mr Davies accepted that he was "partisan", but said his involvement with Privacy International - a watchdog on privacy invasions by governments - was not a secret.
He said the department of information systems had been the driving force behind the report, not him.
He had been one of two mentors whose job it was to inspire those involved in creating the report, he said.
Asked how he felt about the government's reaction to the report, he said: "It's appalling, hypocritical.
"I don't hear the government condemning its own research findings that support the government because they happen to be industry biased experts on board.
"To go in on an ad hominem attack in the way they have indicates to me a level of desperation that indicates just how bad things have gone for the government."
Mr Davies said he had come up with an alternative way of introducing ID cards which would "garner public trust" and urged MPs debating the bill's committee stage to consider it.
He said a lot of time had been spent with the world's top experts in developing "the best ID system in the world" and called for both sides of the argument to work together to develop it.
This would involve applicants going to the post office and having a photo and basic identifying data taken. This would be embedded into a secure application form.
Professionals, such as solicitors, doctors and teachers, would act as referees, endorsing the form, before it is returned to the post office for processing. When the card is ready, the holder would take it to a bank or post office for it to be validated.
However, Home Office Minister Tony McNulty rejected the proposal as "complete and utter nonsense".
"I think his alternative proposal is as preposterous as his original report," he told Today.
"He is talking about getting two referees to stand up someone's identity, temporary databases up and down the country in post offices and banks ....
"There is nothing wrong with being partisan, but he shouldn't pose as an objective and dispassionate academic when he is clearly a partisan in the debate."