Computer crime cost business billions of pounds last year, with financial services bearing the brunt of the damages, revealed a survey from the National Hi-Tech Crime Unit.
It found that more than 80% of large companies were bit by high-tech crime during 2003.
Virus attacks on computer systems were the most common offence, but the greatest harm was done by credit card and bank account fraud, found the survey.
Although only 17% of those companies surveyed had been hit by such fraud, it accounted for almost two-thirds of the financial damage reported.
According to a report, the head of the crime unit, Detective Chief Superintendent Les Hynds, said it was too early to put an accurate figure on the financial impact. He added: "All the indicators suggest billions rather than millions."
The survey, which sampled 201 large companies, found overall damages of more than £195m. Three financial companies reported damage of more than £20m each.
Hynds urged businesses to be more open about reporting cyber attacks, said the report. It said only a quarter of companies hit by high-tech crime had reported it to the police, many because they were concerned about damage to their reputation.
Since the launch of the Hi-Tech Crime Unit almost three years ago, 144 people involved in serious computer related crime have been arrested, said the report.
It said the unit was often hampered by the age of the offenders, with some expert hackers below the age of 14.
