Scrapping plans for a national identity card scheme would cost £40 million, Home Secretary Jacqui Smith said yesterday.
In an attack on the Conservatives, who have pledged to abolish the scheme, Ms Smith said doing so would "not free up a large fund of money to spend on other priorities".
But the Tories accused the Government of deliberately increasing the costs to make it hard for them to abolish the scheme.
During Commons question time, Ms Smith said the Government was "on track" to introduce ID cards this autumn.
She told MPs two contracts would be awarded next month - one to upgrade passport application systems and another for the biometric database for the next generation of passports and ID cards - with the contract for the ID cards themselves being awarded later in the year.
"As is normal, these contracts have been written to protect the public purse with standard clauses in the event of termination," Ms Smith said.
"Cancellation of the ID cards contract and partial termination of the application and database contracts would cost in the region of £40 million in the early years.
"Therefore, as I have made clear on many occasions, scrapping ID cards and the identity database will not free up a large fund of money to spend on other priorities."
Outside the Commons, shadow home secretary Chris Grayling accused Ms Smith of "poison pill" tactics to increase costs for a future Tory administration.
He said: "It looks as if the Government is deliberately making it as expensive as possible for a future Conservative government to scrap ID cards.
"At a time when the public finances are under such pressure, it is simply outrageous for ministers to employ a poison pill strategy against their opponents."