Apple and Google go head-to-head on mobile revenue

Two of the internet's biggest companies are going head-to-head for mobile ad revenue.

Apple has challenged its Silicon Valley rival Google and its plans to expand into mobile devices.

Apple CEO Steve Jobs said that Google's search-based advertisements were not the future for mobile devices, because users tended to spend their time inside "apps" rather than browsing the web.

Apple will launch its iAd network on the iPhone, iPod touch and iPad later this year.

Under the new ad network, Apple would host adverts within their apps and pass on 60% of the revenues to their developers.