Google announced plans on Tuesday to hold a press event next month about its Android mobile phone operating system amid speculation the Internet giant plans to release its own smartphone.

Google invited reporters to attend an "Android press gathering" on January 5 at the company's Mountain View, California, headquarters.

"With the launch of the first Android-powered device just over a year ago, we've seen how a powerful, open platform can spur mobile product innovation," the invitation said. "And this is just the beginning of what's possible."

The invitation provided no further details about the event.

But it comes amid reports Google is preparing to release a Google-branded smartphone known as "Nexus One" which would be sold directly to consumers and would not be tied to any one telecom carrier.

Google employees have been testing the device internally.

A growing number of US telecom carriers and manufacturers have been adopting Google's open-source Android software in bids to challenge the Apple iPhone and Blackberry from Research in Motion.

Although Android's share of the US smartphone market is relatively small, it has doubled in the past year to 3.5 percent in October, according to comScore.

The timing of the Google event appears to be an attempt to upstage the annual Consumer Electronics Show which opens in Las Vegas on January 7.