Google expanded its image advertising space with yet another support: mobile phones. Until now, Google only offered advertisers the ability to purchase text links for mobile devices through its AdWords. The search giant announced yesterday that it introduced brand-image ads for mobile phones. The images are specially designed to fit on mobile phone screens and are targeted according to the keywords users type into phones to search for information.

Google has specific requirements from its ad customers: they have to link to a mobile-friendly page. The pricing scheme is the usual pay-per-click which made Google so successful. Only one image per page will be displayed to avoid cramming of too many elements on the relatively tiny displays on mobile phones.

Alexandra Kenin, a product marketing manager for Google Mobile Ads, said on a company blog that mobile image ads serve as a branding tool and have shown to have good click-through rates. For now, the service is only available in 13 countries: Australia, China, France, Germany, India, Ireland, Italy, Japan, Netherlands, Russia, Spain, the UK, and the United States, Google said.

A text line can be found under the image which makes it clear that the image is an advertisement.

Google has lagged behind other companies in bringing image ads to mobile phones, but so far Internet usage on the go was relatively low. Yahoo, AdMob and Third Screen, which is now owned by AOL, have already used mobiles as advertising platforms.

For the time being, mobile advertising is not a big business, but Google certainly understands that mobile Internet usage will skyrocket over the next few years.