Britain's network of security cameras has been 'an utter fiasco', failing to cut crime despite billions of pounds being spent on it, a senior detective was quoted as saying on Tuesday.

The UK has the most surveillance in the world, according to civil liberty groups and security experts, with an estimated 4.2m closed circuit television (CCTV) cameras on buildings, shops, roads and stations.

But the Guardian newspaper reported Detective Chief Inspector Mick Neville of London police as saying that only 3% of the capital's street robberies are solved using CCTV footage and criminals are not afraid of being caught on camera.

'CCTV was originally seen as a preventative measure,' said Mr Neville, head of the Metropolitan police's division on visual images, identifications and detections.

'Billions of pounds have been spent on kit, but no thought has gone into how the police are going to use the images and how they will be used in court,' he told the Security Document World Conference in London, according to the Guardian.

'It's been an utter fiasco.'

Scotland Yard later said it did not consider that CCTV had failed but did not publicly refute Mr Neville's comments.

It said in a statement that investment in CCTV had helped reduce crime in London.

'We believe that CCTV is an important tool in protecting the public both as a deterrent and in the investigation of a wide range of crime from 'minor' offences to terrorism,' it added.

Mr Neville's comments echo a government report last October which said most CCTV footage is not of good enough quality to help police identify offenders and many cameras are focused on enforcing bus lanes as well as stopping crime.

It said anecdotal evidence suggests that over 80% of CCTV images supplied to the police are not up to scratch.

Mr Neville is now leading an initiative to increase conviction rates from CCTV by setting up a database of images to track down offenders and to put pictures of suspects in crimes such as muggings and rape on the Internet, the Guardian said.

'This has got to be balanced against any Big Brother concerns, with safeguards,' he said.

Work is under way on whether software can be developed to perform automated searches for suspects on footage, while Mr Neville said officers need more training on using CCTV, with many being put off because 'it's hard work'.

The Association of Chief Police Officers said CCTV could be vital in investigations, as had been the case in some terrorism cases, but there are problems because it has been built up in 'a piecemeal way' by organisations other than the police.

'There are questions about how we can make better use of it in the future,' said Graeme Gerrard, Deputy Chief Constable of Cheshire Police, ACPO's lead on CCTV.

'As the police officer quoted in the media today has said, better training and more intelligent use of the technology are important to the future development of how we use CCTV.'