Google said it will hold a briefing about its smartphone business at its headquarters next week as rumors continue to swirl that the Internet search giant is preparing to sell a Google-branded device.

The company emailed invitations to the Jan. 5 event, which it described only as “an Android press gathering,” to the media on Tuesday. Google’s free Android software is currently used as the operating system on more than a dozen smartphones from vendors including Motorola Inc and Samsung Electronics Co Ltd. Android phones, which can browse .........