HTC has finally announced its first two smartphones to feature a 'Facebook' button.

The HTC ChaCha and Salsa were unveiled at Mobile World Congress, which is taking place in Barcelona this week.

Both handsets run Gingerbread, version 2.3 of Google's Android mobile operating system, and come with a button that allows users to post photos, music or maps to the social network.

The HTC ChaCha

The HTC ChaCha features a 2.6in 480x320 capacitive touchscreen and qwerty keyboard, while the Salsa comes with a 3.2in 480x320 touchscreen display. The two smartphones also feature a 600MHz Qualcom 7277 processor and a 5Mp camera, as well as a front-facing camera for video-calling.

Facebook also integrates with HTC's user interface, Sense, so that users can see Facebook messages alongside SMS and MMS messages, while forthcoming events on Facebook are also integrated with the phone's calendar.

The smartphones are expected to be made available in the UK in the second quarter of 2011.

There has been much speculation on whether a Facebook-branded smartphone would actually be made available. The two HTC handsets do not feature the social network's branding but Henri Moissinac, Facebook's head of mobile business, confirmed the social network has "worked closely with HTC".

Earlier this year, Facebook was forced to deny HTC was working on an official Facebook handset.

Last week, INQ also unveiled two new smartphones that integrate with Facebook, run Google Android and focus on social networking.

The INQ Cloud Touch and the INQ Cloud Q are also not Facebook-branded phones, but benefit from Facebook on the homescreen and one-touch links to Facebook Chat, Friends, Messages, Wall and Notifications.

See also: HTC's 2010 sales show surge in smartphone use