Roadside fingerprinting tests, which sparked fears of a Big Brother state when tested in Yorkshire, are to be rolled out nationwide this year.
Every police force in England and Wales will be given hand-held fingerprint scanners to check the identity of suspects in the street.
Senior officers claimed a pilot project, involving 28 forces including West Yorkshire Police, had shown the devices could speed up criminal inquiries, help catch more criminals and save thousands of hours for police. However, although the National Policing Improvement Agency (NPIA) has insisted that scanned fingerprints will not be added to databases, critics fear the scheme could encourage random searches.
An NPIA spokesman said the scheme was voluntary and members of the public had the right to refuse.
But anyone who refused to take part could be arrested and taken to a police station if an officer had "strong suspicions" about them.
Policy director at Liberty Isabella Sankey said: "Convenient technology is all very well but not if it encourages the police to exceed their powers. The public should know that unless you have been arrest-ed or charged there is no power... to demand finger-prints without consent."