• by Mark Walsh  @markfwal, October 5, 2006

Yahoo has started testing mobile paid search in the United States and the United Kingdom after launching its mobile search service in Japan.

Similar to the Web-based version, consumers will be able to click on sponsored search results to go an advertiser's mobile Web site or a landing page for more information.

Previously, Yahoo has conducted only limited trials of its paid search service in the United States. But it struck a deal last month with mobile services firm Bango to allow businesses to buy paid search listings on cell phones.

Yahoo also began providing paid search listings through a deal with mobile directory service go2. For the U.S. beta test, Yahoo is working with a select group of undisclosed advertisers, which it plans to expand over the next few months. The test will run on the networks of the four major U.S. carriers.

Several companies have recently increased their efforts to enter the mobile search market. Last month, Google also began testing mobile search. Also, IAC's citysearch recently launched a "send2phone" feature and plans to soon roll out a mobile search offering.

Overall mobile ad spending is expected to grow to $11.35 billion worldwide by 2011, according to research firm and conference organizer Informa Telecoms & Media.