Kent Police has revealed plans to increase the number of surveillance cameras in the county by a third.

The force will be installing 34 new automatic number plate recognition cameras (ANPR) over the next few years.

There are already a total of 103, which police say have helped solved dozens of crimes.

Last year, images from the cameras were used as evidence in 163 court cases, including murder, robbery, drug supply, money laundering and human trafficking trials.

But campaign group Big Brother Watch has raised concerns about the plans, describing the cameras as "very intrusive".

Research director Daniel Nesbitt said: "When drivers are photographed on them they automatically find their licence plate cross referenced and stored on a database, regardless of whether they are suspected of committing a crime or not.

"Last year, the Surveillance Camera Commissioner criticised the legal basis for the UK's ANPR system.

"With ongoing concerns about the legality and proportionality of the system, now is not the time to be adding more cameras."

Police say they have "extremely stringent" procedures in place to manage the data.

The force's ANPR manager Martin Lyddon said: "Between April 2014 and March 2015 a total of 314 arrests were made as a direct result of stops from ANPR data.

"Between January 2015 and October 2015, 216 vehicles have been seized as having been used in crime or as having been uninsured.

"Around one in every five ANPR stops in the first 10 months of 2015 resulted in an arrest as we continue to effectively use ANPR to deny criminals using Kent’s roads."

He continued: "We want to be very transparent around our use of ANPR in Kent, which is why we are publicising our plans.

"We know that it can be considered by some to be controversial, but it has proven itself as a crucial tool in both detecting and deterring crime.

"We have extremely stringent processes in place to manage the data that these cameras collect and innocent members of the public have nothing to be concerned about.

"Our plans to increase our ANPR coverage across Kent is all part of our on-going commitment to keeping Kent safe and making it as difficult as possible for criminals to operate in our county."

Sites for the new cameras are being considered in Sittingbourne, Faversham, Tunbridge Wells, Tonbridge, Sevenoaks, Dover, Whitfield, Sandwich, Whitstable, Herne Bay, Ashford, Folkestone and Hythe.