The rapid growth of hi-speed access has been blamed as one of the reasons for an increase in certain types of online crime. Broadband users are often more vulnerable to hackers and virus writers who can turn their computers into "zombie" machines, ready to carry out any malevolent command.

The always-on nature of broadband connections combined with the ineptitude of many users to properly secure their connections (no firewall / anti-virus software running etc.) is often to blame.

Unfortunately this has also given rise to a new breed of online crime, cyber-blackmail. Hackers hi-jack systems and then threaten a massive DDoS (distributed denial of service) attack on companies unless they pay up.

Favourite targets for the extortionists -- many thought to come from eastern Europe -- have been casinos and retailers, but one recent high-profile victim was the Port of Houston. "At the end of the day, this is old-fashioned protection racket, just using high-tech," said a spokeswoman for Britain's Hi-Tech Crime Unit.

On Wednesday, UK cyber crime cops made a plea to businesses to report attacks against their Internet businesses following a recent string of incidents with the blackmailing trademark.

Police have seen an increase in the number of distributed denial of service (DDoS) attacks targeting online businesses.

In some cases, the attacks, which can cripple a corporate network with a barrage of bogus data requests, are followed by a demand for money. An effective attack can knock a Web site offline for extended periods.