Cyber-crime cost enterprises in the U.K. a whopping £2.45 billion ($4.59 billion) last year, the country's national computer cops said Wednesday.

According to phone interviews done with more than 200 businesses in Great Britain by the National High-Tech Crime Unit (NHTCU), the law enforcement agency tasked with putting cyber-crooks behind bars, companies with more than 1,000 employees suffered damage in the billions. Smaller firms, meanwhile -- those with between 100 and 1,000 workers -- lost £117 million ($219 million).

"Billions of pounds are being lost to the U.K. economy through hi-tech crime," said Detective Superintendent Mick Deats, deputy chief of the NHTCU, in a statement. "On a positive note, however, we should acknowledge the increased effort put in by companies to protect themselves and their customers from this threat."

The vast majority of businesses -- 89 percent -- had experienced some form of high-tech crime, Deats said. Not surprisingly, the most common form of crime was worm- and/or virus-based: 83 percent said they'd borne the brunt of such attacks. Eleven percent said their network had been illegally accessed or hacked, while 10 percent admitted data had been stolen by e-crooks.

But even such doom-and-gloom stats and the possibility of taking a financial hit haven't moved all British businesses to take security seriously. Nearly three out of four firms interviewed by the NHTCU, for instance, believe that their company is devoting sufficient resources to deterring cyber-crime, while over a third said that their firm doesn't do regular security audits.

"Over the past year, we have seen a sustained increase in the professionalism of cyber-criminals," warned Deats.

The full report can be downloaded in PDF format from the NHTCU Web site.