Police are planning to store data captured by a proposed national automatic number plate recognition (ANPR) camera network for at least two years.
The government last year announced plans to develop a national network of thousands of cameras that can automatically scan car number plates and check them against police databases.
If a passing car was linked to a reported crime, police would be able to act.
Now the Association of Chief Police Officers (Acpo) has said it plans to collect the data in a searchable database that can be used in police investigations for at least two years.
Acpo says there may also be a case for keeping some of the data for over two years.
This possibility is believed to be linked to the tracking of what police view as career criminals, who are expected to commit crimes in the future. The extended availability of this information would provide extra intelligence to the police.
The government said the Acpo recommendations complied with the European Convention for Human Rights, data protection laws, the Regulatory Investigative Powers Act 2000, and the Freedom of Information Act 2000.
The police are currently involved in a £15m pilot of the technology. A national intelligence centre is being considered to fully analyse data collected, if the technology is rolled out nationally.