No-one in the intelligence services will be pressing for the introduction of identity cards, the former head of MI5 Dame Stella Rimington has said.
The Home Office says a stand alone card will cost £30
"I don't think they are necessarily going to make us any safer," she told the Association of Colleges conference.
And they would be "absolutely useless" if they could be forged as easily as other identity documents, she added.
The former security chief was speaking shortly after the government suffered a defeat in the Lords on ID cards.
Peers backed a Conservative amendment to ensure that only those who reasonably require proof should be entitled to ask for verification of identity.
Dame Stella told the Birmingham conference: "ID cards have possibly some purpose.
"But I don't think that anybody in the intelligence services, particularly in my former service, would be pressing for ID cards.
"My angle on ID cards is that they may be of some use but only if they can be made unforgeable - and all our other documentation is quite easy to forge.
"If we have ID cards at vast expense and people can go into a back room and forge them they are going to be absolutely useless."
A spokesman for the prime minister said later that Dame Stella was a private individual and entitled to her views. The Home Office had made its case for ID cards, he added.