More than two-thirds of UK businesses surveyed reported that they were victims of high-tech crimes last year, costing them millions of pounds in down time, systems damage and client loss, according to a report released Tuesday by the National Hi-Tech Crime Unit (NHTCU).

In a survey of 201 large and medium-size companies, 83 percent said that they had experienced some form of high-tech crime last year, such as virus attacks, fraud and criminal use of the internet by employees, costing them more than £195 million, according to the NHTCU.

However, NHTCU head Len Hynds estimated that the real loss to UK businesses was in the billions of pounds, since 90 percent are small enterprises, not accounted for in the survey.

"Although it's too early to put an accurate figure on total financial impact ... all indicators suggest we are talking about billions rather than millions," Hynds said, speaking at the e-Crimes Congress in London on Tuesday.

The survey asked companies to consider factors such as employee and business downtime, client loss and erosion of public image as contributing to their losses.

Of the £195 million reported lost by the companies surveyed, £60 million alone was lost by three financial institutions that experienced fraud and extortion, Hynds said. The report kept the names of the institutions confidential.

The highest incidents of high-tech crime reported were related to virus attacks, however, with 77 percent of surveyed businesses saying that they had suffered attacks last year. Of these, companies said that they experienced on average 254 attacks.

Meanwhile, 20 percent of the companies surveyed said they experienced denial-of-service attacks, and 11 percent said they experienced system penetration.

Seventeen percent of companies surveyed reported financial fraud and 11 percent experienced data theft.

On the security front, only 77 percent of the companies surveyed carried out regular security audits, however, and only 31 percent had formal crisis management teams.