In the final three months of 2008, click fraud surged to a new high as criminals had thousands of hacked computers pretend to be customers checking out online ads, according to a report released Wednesday.

According to Click Forensics, a US firm that audits Internet traffic, 17.1 percent of clicks on online advertising were frauds evidently intended to boost the number of clicks and drive up bills for businesses paying per click.

The rate was 0.5 percent higher than the figure reported in the same quarter a year earlier.

Networks of hacked computers referred to as botnets are said to be responsible for nearly a third of the click fraud in final three months of 2008.

According to Click Forensics president Tom Cuthbert, It seems that the online advertising industry is not immune to the growing tide of cybercrime during this recessionary period, said Click Forensics president Tom Cuthbert; the AFP reported.

Both the overall click fraud rate and the rate of click fraud originating from botnets were the highest ever in Q4 2008. Advertisers should pay close attention to these types of threats.

The rate of fraudulent clicks is 28.2 percent.

The fraudulent clicks on advertising at Internet search engines, including Google AdSense and Yahoo Publisher Network, represented a tenth of a percent drop from that reported in the final quarter of 2007.

Various internet firms, among which are Yahoo and Google, rely heavily on revenue from pay-per-click ads and employ technology to expose bogus clicks so advertisers will not have to pay for those clicks.

According to Click Forensics, there are varying motives for the fraud including boosting the commissions earned on ads and also driving up expenses for competing businesses.