Amazon.com Inc said Wednesday it has struck a sponsorship deal with AT&T Inc to sell a less expensive version of its Kindle 3G digital reader.

Amazon's Kindle 3G, which allows users to buy electronic books without having to subscribe to a wireless network, costs $189. The AT&T sponsored device, which will also include built-in ads on its screensavers, will cost $139.

Amazon in April introduced built-in advertising from companies such as General Motors Co's Buick, Procter & Gamble Co's Olay, and Visa Inc, on a different version of the Kindle, which competes with devices such as Barnes & Noble Inc's Nook and Apple Inc's iPad tablet.