Industry buzz points to Facebook smartphone, a modified version of the Android operating system in an association with HTC

Facebook will next week unveil its latest push into the mobile world – and industry watchers are convinced the social network is about to launch a Facebook-branded phone.

Media has been summoned to an event at Facebook's headquarters in California on 4 April, with teaser invitations bearing the words "Come See Our New Home on Android".

The world's largest social networking site is giving no further clues, and the announcement could be nothing more than a new service or application, but detailed leaks suggest the company is about to release the fruits of a long-rumoured collaboration with Taiwanese manufacturer HTC – a smartphone whose software is a customised version of Google's Android operating system.

While the camera and memory are reportedly run of the mill – a modest 5 megapixel rear lens for photos, a 1.6 megapixel front facing camera for video calls, and a basic 16 gigabytes of storage – its software may be unique.

With a similar look to a black iPhone but boasting a slightly larger 4.3 inch display, the phone is supposedly packed with Facebook services, with easy access to its instant messaging and Instagram photography applications, and a home screen displaying the owner's news feed.

Facebook founder Mark Zuckerberg has made no secret of his desire to do more for the 680 million people who access his services on their mobiles each month.

"You have a good version of all the Facebook features you know and want on your phone. So now the next thing we're going to do is get really good at building new mobile-first experiences," Zuckerberg told investors in January. "That's going to be a big theme for us this year."

An advertising campaign is being created in southern California for HTC and Facebook, under the strapline "more than just an app", the 9to5Google website reported on Thursday.

"The advertisements are designed to focus on the potential user of the device, not on the hardware or software," reporter Mark Gurman wrote.

The project may be called Facebook Home according to TechCrunch, and its software will be a tweaked version of Android with Facebook built-in functions, but not a full rewrite as used in Amazon's touch screen Kindle Fire tablet.

In recent weeks details for the Facebook phone have been published on Twitter by two anonymous sources, one of whom is close to HTC and relied on by developers for unofficial updates on the manufacturer's plans.

In January @LlabTooFeR published full details of the phone's camera, screen size and processing power. The source claimed HTC and Facebook were developing a handset codenamed Myst, that would be available on the US network AT&T, would be 4G compatible, and would have a physical Facebook button. This month @evleaks, another source of early news on mobile development, published a similar list of specifications.

If the rumours prove correct, the phone will be HTC and Facebook's second collaboration in three years. The first was not a success.In 2011 the HTC ChaCha and Salsa phones appeared, featuring a Facebook button which lit up when the user activated the networking site.

When pressed, the F-button would post a recently taken photo or favourite website link to the owner's Facebook page. The devices were discontinued a few months after launch.