The Kin One and Kin Two phones, which both feature touchscreens and slideout keyboards, will be sold in Britain, Germany, Italy and Spain in partnership with Vodafone.

Microsoft did not announce prices for the phones, which are aimed at countering similar devices from rivals.

The US software giant worked closely with Sharp to develop hardware for the Kin series aimed at the youth market.

Unlike most popular smart phones, the Kins won’t have access to application stores that let customers download add-on software programs, with Microsoft instead opting to focus on social networking.

“Social networks are the cornerstone of this experience,” Derek Snyder, a product manager at Windows Mobile, said at an unveiling event for the new phones in San Francisco.

“We saw an opportunity to design a mobile experience just for this social generation – a phone that makes it easy to share your life moment to moment,” Robbie Bach, president of Microsoft’s Entertainment and Devices Division, added.

The Kin phone home screen stays on at all times as the device brings together feeds from social networks such as Facebook, MySpace and Twitter.

Videos, photos, text messages, web pages and location and status updates can be shared by dragging them to a place on the phone called the Spot, a green spot permanently showing in the corner of the screen.

The Kin One features a five-megapixel camera which shoots standard definition video and is smaller and more compact than the Kin Two.

The Kin Two has a larger screen and larger keyboard, more memory and an eight-megapixel higher resolution camera which can record high-definition video.

The Kin can store photos and video online through a feature called Kin Studio, which also backs up text messages, call history and contacts.

It also allows users to listen to music or watch video from the Zune Marketplace, the online store for Microsoft’s Zune MP3 player.

The Kin One has four gigabytes of memory, or room for about 1000 songs, while the Kin Two has eight gigabytes of memory or 2000 songs.

The phones are black and the touchscreen gestures are similar to those used to operate Apple’s iPhone.

The phones are meant for people who wanted a handset that worked simply, without forcing them to hunt through menus and icons, Kin team leader Roz Ho said.

Ms Ho said her team studied consumer habits and then built the activities they used most often into the phones.