In a speech to a Confederation of British Industry (CBI) seminar in September 1997, Graham Saltmarsh of the South East Regional Crime Squad said the police cannot help companies beat the digital criminals. "Funding constraints will reduce the ability of police forces to support industry," he said. He recommended that companies "develop their own capabilities in investigation and intelligence gathering".

Who needs a getaway car?

Chris Sundt, the head of the CBI's Information Security panel, is unhappy about Mr Saltmarsh's proposal that companies should take the lead in investigating crimes they suffer. "You have got to be careful with self policing," he said. "There is a fine line between watching what people are doing and becoming a private police force."

His concerns are echoed by Jonathan Sowler, head of consulting for the London computer security company JCP: "It is a very difficult area for national police forces, there are resource issues as they move into new areas."

But the CBI's concerns about the police telling business to investigate their own crimes are not purely ethical. "That does separate out the large corporations from the small companies who don't have the resources to mount an investigation," says Mr Sundt.

Computers must be handled correctly after they are seized

"Small companies are the most vulnerable," he continued. "It may be some time before they realise they have been hit."

And while the Computer Crime squad based at New Scotland Yard is only big enough to handle a few cases, Mr Sundt believes most policemen have little idea about what to do when starting to investigate online crime. "Police forces have not got enough people geared up to understand the way computers work," he said.

Even if a computer's hard disc has been wiped it is possible to get vital clues from it, if you have the right sort of forensic software. A PC allocates 32k of hard disc space to every block of data, and it is almost impossible to completely delete it.

But although specialist forensic computing companies are being formed, the detailed knowledge required to unlock the secrets of a reformatted hard disc is still beyond many detectives.

"They should have more people with that sort of expertise," says Chris Sundt. "If local police do not create the level of expertise to support small companies that is not an adequate response."