Google’s Android unit is reportedly working on a wearable smartphone that would be a rival to Apple’s much talked about – yet still unseen – iWatch.

Wearable technology has become an increasingly hot topic, with Apple ’s iWatch and the smart spectacles Google Glass dominating the headlines.

Whilst Google Glass has been tested in public and is due for launch towards the end of this year, details about Apple’s iWatch have come from a series of rumours and supposed leaks.

Some reports have said the iWatch is heading into production, whereas others have suggested it is still a number of years away.

Similarly, a Google smartwatch has not been confirmed, but is working on has not been confirmed, but came via an insider briefing to the FT .

The leak would, however, seem to be confirmed by the fact that last year Google had a patent application approved for a “smart watch” with dual-screen “flip-up display”, and a camera.

The patent filing also mentioned a “tactile user interface” – or touchscreen.

The reported Google device is separate from the Samsung smartwatch, which the Korean firm this week confirmed that it is working on.

Concept for a Samsung watch by Johan Loekito - Google is working on a separate device.

“We’ve been preparing the watch product for so long,” Lee Young Hee, executive vice president of Samsung’s mobile business, told Bloomberg during an interview in Seoul.

“We are working very hard to get ready for it. We are preparing products for the future, and the watch is definitely one of them.”

The challenge facing smartwatch designers is miniaturisation. All the main technologies – screens, processors, GPS, mobile software, Bluetooth wireless networking – are already mature and in mass use.

The problem is fitting them into something small enough to look stylish on a wrist.