Microsoft has unveiled Surface - its own-brand family of tablets, BBC reports.

The touchscreen computers will be powered by its upcoming Windows 8 system and contain a choice of an Intel or ARM-based processor.

It allows the firm to challenge Apple's bestselling iPad with a device that can run standard applications such as its own Office programs and Photoshop.

But it puts Microsoft in competition with other manufacturers planning to release tablets designed for Windows 8.
The company's chief executive, Steve Ballmer, said he had wanted to give the software "its own companion hardware".
The devices have 10.6 inch (26.9cm) displays, built-in kickstands and are housed in magnesium cases - which the company described as the first of their kind.

The ARM-based tablets are 9.3mm (0.4 inches) thick - slightly less than the iPad - and run the Windows RT version of the new system. The Verge reported that the chipset will be built by Nvidia.

The versions using Intel's x86 technology run Windows 8 Pro and are 13.5mm (0.5 inches) thick.

The specifications mean the Surface tablets have bigger screens than the iPad but are heavier.