Civil liberty campaigners have called on Kent Police to review the use of automatic number plate recognition surveillance cameras after a ruling their use by another force was unlawful.

Hertfordshire Police has been ordered by an information watchdog to dismantle cameras around the small town of Royston.

The Information Commissioner said their use was excessive and not proportionate in a ruling that followed complaints from civil liberty groups.

Nick Pickles, director of privacy at Big Brother Watch, said the ruling against Hertfordshire Police had implications for Kent.

The county force has been at the forefront of using surveillance cameras to tackle crime since 2001.

Mr Pickles warned Kent Police could face a similar challenge.

He said: "Police forces have to abide by the Data Protection Act like everyone else and I am seriously concerned some forces are pushing the law to breaking point in how they use ANPR cameras.

"Kent Police should be absolutely transparent about what data they collect, how long they store it and why.

"It is unacceptable, as the Information Commissioner's ruling makes clear, to be routinely recording details of every car journey made in Kent and if they are doing so, I will be asking the Commissioner to urgently investigate."

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Stephen Eckersley, head of enforcement at ICO, said it was difficult to see why Royston required cameras to monitor all traffic 24 hours a day.

"The use of ANPR (automatic number plate recognition) cameras and other forms of surveillance must be proportionate to the problem it is trying to address," he said.

Like most forces, Kent Police uses a combination of fixed cameras, mobile cameras and vehicle cameras.

It has around 150 cameras and, according to data, the force made 1,226 searches against the National ANPR Data Centre in 2011-12.

Kent Police said it was waiting for the outcome of a national review of the use of such cameras before deciding if it needed to reassess its own policy.

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