Plaid Cymru and the Welsh Liberal Democrats have pledged to oppose the introduction of identity cards.

Following the government's publication of draft legislation on Monday, both parties set out their opposition to the proposed scheme.

The Welsh Lib Dems called on Rhodri Morgan's Cardiff administration to explain its views on the cards.

While the nationalists raised concerns about the cost of the home secretary's scheme.

"David Blunkett has refused to disclose how much this scheme is going to cost although people estimate it could be as much as £3 billion," said Plaid policy director Simon Thomas.

"That is more than the entire NHS capital budget for 2003/04 or the cost of some 60,000 extra police officers.

"Should the government really be spending billions on ID cards when firstly, there is no correlation between the use of ID cards and crime rates in western countries, and secondly, the Welsh Assembly Government has already stated it has no intention of using ID cards as a passport to public services?"

Thomas also warned that the plans would "make the people subject to the government".

"Plaid Cymru therefore opposes the introduction of ID cards both in practice and in principle," he said.

For the Lib Dems, assembly member Jenny Randerson said it would be "bad in principle and bad in practice".

She is to hold a debate in the Cardiff assembly this week in a bid to force the assembly government to set out where it stands on the plans.

"The assembly needs the chance to debate the issue, particularly as their introduction poses significant questions regarding entitlement to those public services, which fall under the assembly's remit," she said.

"The first minister has spoken of it only as a long-term issue, yet the home secretary seems intent on introducing them as soon as possible."

She added: "If the voluntary card is an accessing device for public services, then for those most needy it will become a de facto compulsory card.

"This is likely to lead to true compulsory cards, which would be unnecessary and intrusive, but would fit in with Blunkett's big brother ambitions."