Civil liberties campaigners have expressed alarm that millions of car journeys are to be stored on a national database for five years.

Already some 10 million journeys a day are being recorded using automatic number plate recognition (ANPR), but this is set to rise to 50 million.

It will be collated at a new National ANPR Data Centre in Hendon, north London, for use by police.

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While the original period for which the data was planned to be held was two years, the Home Office has confirmed that it was now being kept for five years.

The disclosure came after a freedom of information request by The Guardian.

The paper has also obtained an Acpo ANPR strategy document advising officers to “fully and strategically exploit” the data gathered.

• A d v e r t i s e m e n t

Simon Davies, director of Privacy International, said the database gave police “extraordinary powers of surveillance” that were “unnecessary and disproportionate”.

He added: “This is possibly one of the most valuable reserves of data imaginable.”