Rory Cellan-Jones reports from Google's launch event in California
Google has unveiled an own-brand smartphone called the Nexus One.
The wraps were taken off the handset at an invitation-only event held at Google's Mountain View HQ.
The Nexus One is a slim, touchscreen phone built in partnership with Taiwanese manufacturer HTC and runs Google's Android operating system.
It will be sold via Google's website and initially be available on T-mobile in America followed by Vodafone in Europe and Verizon in the US.
Direct from Google it will cost $529 (£331) and on contract with T-Mobile $179 (£112). Google said the phone would ship from launch day.
Mario Queiroz, Google vice president for product management, described the unveiling as "the next stage in the evolution of Android".
Mr Queiroz said there were now more than 20 Android phones available from 59 carriers in 48 nations.
The release of the Nexus One is seen as a move to ensure Google remains relevant as people search the web using mobile phones rather than typing queries into a PC.
Google makes the lion's share of its revenue by selling adverts linked to those queries.
NEXUS ONE HANDSET
3.7 inch touchscreen
1GHz snapdragon processor
5 Megapixel camera with LED flash
GPS and compass
Noise cancellation technology
Voice recognition can be used with all applications
Light sensor changes screen brightness to conserve power
512MB Flash memory with SD card slot (expandable to 32GB)
At the briefing, Google said the Nexus was "a point of convergence where the web meets phone and is an example of what is possible on mobile through Android."
"You will see it pushes the limits of what is possible on a mobile phone today," said Peter Chou, HTC chief executive.
Google has set up its own phone portal through which people can get a handset tied to one of several mobile operators or untethered direct from the search firm.
Gartner analyst Carolina Milanesi said this could be its main selling point as it would mean owners could decide which network to sign up with.
"You buy the phone and then choose what sim card you want to put in," she said.
Those buying an unlocked phone would be able to use it as a GSM phone on almost any network.
A spokesperson for Vodafone told BBC News that it was the first operator to "bring the Google phone to the UK" but stressed that it was a "non-exclusive agreement", meaning other networks could also offer the phone soon.
He said it would be available "in the coming weeks" but only from Google's website.
Figures from Gartner suggest that Android has about a 3.5% share of the global smartphone market. By comparison Nokia has a 39% share and Apple 17%.
It emerged on 5 January that Google sent out Nexus One phones to some industry figures in mid-December so they can try them out. Recipients were asked to keep quiet about their experiences until 5 January.
"The Google phone isn't much different than the iPhone," wrote VC Fred Wilson from Union Square Ventures on his blog. "It's basically an Android clone of the iPhone."
Google also announced on 5 January a plan to launch "pay to call" adverts that would appear on mobile phones. These would work in a similar way to the "pay to click" adverts that populate many websites and which form a significant chunk of Google's revenue.
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