The streets of Brighton and Hove are being monitored by up to 20,000 security cameras.

Newly-released Home Office statistics reveal there are more cameras in the city than anywhere else in Britain apart from London and Manchester.

The number of security cameras makes the people in Brighton and Hove among the most watched citizens in the country.

But the increase in public and private cameras, watching people's every move, has sparked claims of "overkill" from civil liberties group Liberty. A spokesman said: "CCTV is not a magic bullet. It is not a substitute for police officers on the beat and in most circumstances better lighting will deter crime rather than banks of cameras.

"People often feel very uncomfortable being surrounded by hundreds of cameras and in our opinion they often do very little other than monitor innocent citizens. It does create a big brother society and although there are some benefits it is mostly overkill."

There are also plans to further the "big brother culture" in the city with airport security style barriers at railway stations and automatic number plate recognition systems on the roads.

The most marked increase in CCTV cameras has happened since 2001 and the 9/11 bombings.

Many security cameras line roads in and out of the city. Government estimates reveal the number of CCTV cameras used by police and other public agencies in Brighton and Hove at around 10,000. The rest are those employed by shops, banks or other businesses and even now in taxis.

A Home Office spokesman said: "CCTV cameras are an extremely useful tool for all sorts of people, not just the police. They help secure private companies and make people feel safer while going about their business.

"CCTV is not a cure-all but it is a very useful method of reducing crime and making an area less dangerous."

Taxi driver Phil Sim, 39, from Brighton, is one of a number of cabbies who now have security cameras in their cars.

He said: "If people get in the car and clock the camera they will be far less likely to act up or misbehave. It works very well for me and a lot of other drivers I know. It makes us feel safer."

The 7/7 London bombings have also increased the likelihood of other monitoring devices being installed.

Airport style security barriers, which have been trialled at London railway stations, are expected to be brought in at Brighton and Hove stations if the experiment in the capital is a success.

Their use is a direct response to the London bombings and are designed to detect weapons or bombs.

Brighton's Transport Police chief Gary Ancell has welcomed the idea but commuter groups believe they could lead to long delays.

A decision on the barrier and potential roll-out is expected in April.

The Government has announced further plans to install more automatic number plate recognition cameras in the country. They will track vehicles and record instances of mobile phone use behind the wheel.

Sussex Police has confirmed it is a supporter of the cameras.