Google may have just outed a new addition to its Nexus tablet range, Digital Spy said.

A mystery Android slate has cropped up in a document detailing the Android L operating system, sandwiched between a Chromebook and a Nexus 5.

The device in question is the wrong shape for a Nexus 10 and appears too large to be a Nexus 7, adding fuel to reports that a 9-inch addition to the tablet line is on the way.

Although the tablet may be a render, it seems unlikely that Google would use a generic device in an official document when it has existing products it could be featuring.

HTC is rumoured to be developing a tablet for Google, which could launch under the moniker of the Nexus 9.

The Nexus 9 is rumoured to feature an 8.9 inch 2048 x 1440 display, an NVIDIA Tegra K1 64-bit processor, and 2GB of RAM.

Pricing is said to start at $399, a significant step up over the original Nexus 7.