Annual spending on mobile search advertising will reach $445m in 2008 and is predicted to rise to more than $2bn by 2013, according to Juniper Research.

The analyst firm highlighted the key role of mobile search applications and services within the mobile advertising environment.

As operators abandon the 'walled garden' model, consumers are increasingly searching for content both on and off-portal, providing a substantial target audience for advertisers.

"Mobile advertising was historically dominated by campaigns conducted almost exclusively via SMS," said Dr Windsor Holden, principal analyst at Juniper Research.

"But the mass adoption of 2.5G and 3G handsets, combined with more applications enabling targeted instant measurement and frequency capping, mean that consumers can now receive personalised advertising across a variety of rich media channels."

Juniper predicted that total mobile ad spend will rise from $1.3bn in 2008 to more than $7.6bn in 2013, and that mobile search revenues (including data charges) will reach $4.8bn by 2013.

The Far East and China are expected to lead the charge in mobile search ad spend and total mobile ad spend, followed by Western Europe and the US.

However, the report highlighted the potential for advertising across a host of delivery mechanisms, including MMS and idle-screen advertising, which could be worth as much as $1bn within five years.