A closed circuit television system described as the most advanced and largest in the UK is being officially switched on in Manchester on Friday.

The �3m operation uses digital technology to cover the whole of the city centre, with 400 cameras.

Footage can be retrieved immediately, over a 13-week period, cutting out the need to look through hours of video tape.

The system has been on trial since February, and cameras are operated from a control centre where the images they record are seen on a 60-feet wall of monitors.

The aim is to cut street crime

Chief Inspector Brian Lawton from Greater Manchester Police said: "It is extremely effective - we have been running 50 arrests per month as a direct result of this new system.

"People have got nothing to fear and everything to gain - it is controlled strictly by data protection and we have safeguards in place as to what we do with the images which we capture."

Organisers say the scheme is the largest single security camera project controlled from one centre in the country.

Home Office Minister Lord Falconer, who is unveiling the scheme, said: "Crime overall is down, but street crime - mainly robberies - has continued to rise."

'Fantastic' facility

The project is jointly funded by Manchester City Council together with car park firm NCP Manchester Limited.

Bill McLane from NCP said: "We have individual persistent offenders picked up on the big screen monitors.

"Most of these individuals are known to the operators and they can be met... so hopefully any potential criminal that wants to come to Manchester will be ejected fairly quickly."

Councillor Kath Robinson, deputy leader of Manchester City Council, said: "This fantastic new facility will allow us to continue to protect individuals and stakeholders and their peaceful enjoyment of our magnificent city centre."