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

AT&T sponsoship for the Kindle 3G means that the device is now available at a new price of $139. The 'Kindle 3G with Special Offers' is the same as the $189 Kindle 3G, but it incldues built-in ads on its screensavers.

"Kindle 3G is more convenient - customers never have to hunt for or pay for a Wi-Fi hotspot - they simply download and read books anytime, anywhere. Kindle 3G customers read 20 percent more books, and take advantage of twice as many special offers," said Jeff Bezos, Founder and CEO, Amazon.com. "A big thank you to AT&T for helping to make the new $139 price possible."

Kindle 3G includes free 3G wireless, paper-like Pearl electronic ink display, access to Kindle Store and integration with free "Buy Once, Read Everywhere" Kindle apps for iPad, iPod touch, iPhone, Android, PC, Mac, BlackBerry and Windows Phone.

Amazon.com is also reportedly planning to release its first tablet computer in October, the Wall Street Journal reported on Wednesday, citing people familiar with the matter.

The company will also release two updated versions of the Kindle electronic reader in the third quarter, one of which will be a touchscreen device, the paper said.