The U.S. Federal Trade Commission won't block Google's US$750 million acquisition of mobile advertising vendor AdMob because the deal isn't likely to harm competition in the emerging mobile advertising market, the agency said Friday.

Google has started supporting a click-to-call feature in AdWords on mobile smartphones.

Opera has acquired AdMarvel, which has developed a product suite that manages how ads are delivered to mobile phones, the Norwegian Web browser company said on Wednesday.

The importance of advertising as a revenue source for developers will grow as users become less willing to pay for mobile applications, according to market research company Gartner.

Google is introducing a mobile marketing campaign for Place Pages, a service for businesses that faced some early criticism when it launched in September.