In 2005 the government invested £32m to develop the ANPR data-sharing programme after police concluded that road traffic cameras could be used for counter-terrorism and everyday criminal investigations. Senior police officers have said they intend the database to be integrated into “mainstream policing”.

Half of all police forces in England and Wales have now been connected to the network, reading between 8 and 10m licence plates a day. The Association of Chief Police Officers (Acpo) said the database would be linked to ANPR systems run by all but two police forces by the end of the year. The database will be able to store as many as 18 bn licence plate sightings in 2009.

The Acpo ANPR strategy document, obtained under the Freedom of Information Act, envisages the database will be used at all levels of policing. The document, which sets policy up until 2010, states that police forces should “fully and strategically exploit” the database.

Officers can access the database to find uninsured cars, locate illegal “duplicate” licence plates and track the movements of criminals. The Acpo adds that the database will “deter criminals through increased likelihood of detection”.

“Experience has shown there are very strong links between illegal use of motor vehicles on the road and other types of serious crime,” said Merseyside Police’s Assistant Chief Constable, Simon Byrne, who leads Acpo’s ANPR policy.

The director of Privacy International, Simon Davies, said last night the database would give police “extraordinary powers of surveillance”. “This would never be allowed in any other democratic country,” he said. “This is possibly one of the most valuable reserves of data imaginable.”

Peter Fry, of the CCTV User group, said that licence plate images captured by CCTV are generally retained for 31 days. “There’s not a great deal of logic to explain keeping the same images for five years,” he said.