Google finds new advert options

Google, the world's most-used internet search engine, is testing a form of online advertisements where clients pay only when web surfers click on an ad and buy a product or generate a sales lead.

The company said it was testing so-called "cost-per-action" ads on its AdSense advertising network. The AdSense program lets third-party publishers, such as writers of web logs, show ads sold by Google on their sites.

Google is expanding its range of ad options as it seeks to sustain surging advertising sales, which almost doubled to US$6.07 billion ($9.9 billion) last year. The company also has added graphical and video ads to give companies more ways to promote products online.

"We're pleased with how the test is progressing and will continue to gather feedback from advertisers and publishers," Google said.

Shares in Google ended Thursday's Nasdaq trading at US$399.95, having fallen about 7 per cent so far this year.