The Home Office said a mandatory database "would raise significant practical and ethical issues".
Home Office minister Tony McNulty told BBC that a national database was not a "silver bullet" and that it would raise practical as well as civil liberties issues.
"How to maintain the security of a database with 4.5m people on it is one thing," he said.
"Doing that for 60m people is another."
Politicians listening to reason and experts and not going to do something (that can be spun as doing something useful) because it's impractical? Who are you and what have you done with the real politicians?