Identity cards were rolled out to foreign nationals last year
The Scottish Government has told Westminster it remains "completely opposed" to its plans to roll out identity cards across the UK.
In a letter to the Home Office, Community Safety Minister Fergus Ewing said the cards posed an "unacceptable threat" to civil liberties.
He was responding to a consultation on a code of practice relating to the scheme, which is a reserved matter.
The rules must be in place before the first cards are issued to UK citizens.
Mr Ewing told junior Home Office minister Meg Hillier that money allocated to the scheme would be better spent on more "worthy" causes, such as schools and hospitals.
He said: "Given the current financial climate, the UK Government should have better uses for the vast sums of money being spent on this scheme, which presents an unacceptable threat to citizens' privacy and civil liberties, with little tangible evidence to suggest it will do anything to safeguard against crime and terrorism."
His letter also sought "clarification" on some of the detail of the proposed regulations and queried the legality of the national identity register under European human rights rules.
Mr Ewing said the overall costs of the scheme could be £4.8bn UK-wide, rising to £5.11bn if costs associated with foreign nationals were included.
"This money could and should be used to pay for much more worthy causes like more teachers, nurses or police officers or more schools and hospitals," he said.
He also questioned the price of the cards.
He said: "All citizens, including Scots, will be expected to fork out for a card and to enrol on the national identity register when this becomes compulsory in 2012.
"The initial application fee has been fixed at £30 and that is supposedly a cut-price offer to entice citizens to get one before they become compulsory. How much they will cost from 2012 is anyone's guess."
A Scottish Labour spokesman claimed two-thirds of people in Scotland supported ID cards.
He said: "As schools go without teachers, hospital infections go untackled, and the police make cutbacks, all they can do is send a letter to Westminster about an issue for which they have no responsibility.
"They should respect the will of the Scottish people who voted for devolution, and stop picking political fights on issues which are reserved to Scottish MPs to deal with."
The Scottish Parliament voted against the UK Government's plans to introduce ID cards in November last year.
MSPs backed a Scottish Government motion stating the scheme would not increase security or deter crime, while raising concerns about civil liberties.
Identity cards were rolled out to foreign nationals living in the UK in November 2008, while the Home Office said it expected to issue the first ID cards to British citizens later this year.