Microsoft's chief executive said his company would not miss any possible opportunities to build its own devices, after the launch of its Surface tablet last month. "Do I anticipate that partners of ours will build the lion's share of all Windows devices over the next five years? The answer is, absolutely," Steve Ballmer said at a tech industry event in Santa Clara, California, on Wednesday.

"With that said, it is absolutely clear that there is an innovation opportunity on the scene between hardware and software and that is a scene that must not go unexploited at all by Microsoft," he added.

Ballmer's words potentially bring the software giant into competition with its hardware partners and opening the door to a Microsoft-branded phone. Microsoft has already built its own Surface tablet, and making more devices would put the company into direct competition against manufacturers like HP, Acer and Lenovo.

Last week reported surfaced two weeks ago that Microsoft was already testing a design for its own phone, but the company has not confirmed it.