Google and Motorola are working on a smartphone to challenge Samsung and Apple and it could be unveiled at the search giant's Google I/O conference on May 15.

Stories of this new flagship Android handset, the first that Google will have made with Motorola -- the struggling handset manufacturer that Google acquired last year, have been slowly building over recent months. The latest rumours come courtesy of Android site Droid Life which has been analyzing a 600-page forum thread on the subject, passed to it from a reliable Motorola source.

Reportedly, the X Phone will come with a number of preloaded apps and will be available on all of North America's major carriers when it goes on sale in July. Google has a well-documented history of partnering with smartphone manufacturers to develop Nexus handsets that are meant to be reference points for the Android community of phonemakers and developers; the most recent of which, the LG-built Nexus 4, has proven such a hit that it is constantly sold out. However, what sets this phone apart from earlier collaborations is that it will not carry the Nexus branding. This has led many in the tech community to speculate that this will be a true Android 'flagship' phone that can compete in terms of quality as well as functionality with the best that Apple and Samsung has to offer.

According to a report in the Wall Street Journal, which has been tracking the story since December, a number of features such as a flexible screen are currently being considered and the partnership will eventually yield an X Tablet as well as the aforementioned phone.