Yahoo on Wednesday announced the launch, in beta, of paid-search ads for its mobile service in the U.S. and the U.K.

A "select group of advertisers" are participating in the test of sponsored listings on mobile web search results, according to the Search Engine Watch blog. The number of advertisers will increase as the program is rolled out. Consumers who click on the sponsored links will be taken to the advertisers' mobile website or a landing page to get more information about the advertisers' offerings and will be able to call the advertiser.

Yahoo had already been testing mobile sponsored search in Japan and the U.K. In early September, Google announced that it was testing a mobile version of its popular AdWords ad offering, MediaWeek points out.

Response rates of mobile pay-per-click ads tend to be higher than online because of increased relevance and reduced ad clutter.

Yahoo's Mobile Web service, available on most mobile phones via major operators in the U.S. and U.K., provides access to Yahoo's Mail, Messenger, Search, News, Finance and Sports services.