Anti-war protesters and train spotters arrested under anti-terror laws could have their DNA kept for life under Home Office plans.
In the UK innocent members of the public detained but not charged or convicted under terrorism legislation may never have their profiles wiped from the national database because they are to be treated differently to all other alleged offences.
The proposal is directed at those arrested for suspected terror offences but could apply to anyone held under a Terrorism Act.
In contrast, those innocent of any other suspected crime will be kept for a maximum of six years.
The proposals have been drawn up in the wake of a European Court of Human Rights ruled last year that a blanket policy of retaining profiles of innocent people indefinitely was illegal.
Up to a million innocent people are currently held on the national database.