Google has said it is defending its online advertising empire with the launch of its own brand mobile phone.

It is the first time Google has designed and sold its own consumer hardware device.

Google said the Nexus One represented the next frontier in the company's $20bn (£12.4bn) core business - selling advertising through search.

"It's all about the mobile web, and advertising is their bread and butter," said analyst Michael Gartenberg.

"It's the latest salvo from Google on the wireless industry. The landmark news here is that Google is now a consumer electronics retail company," added Mr Gartenberg, of Interpret.

Google, like many in the industry, recognises that more and more people are accessing the web via their mobile phones rather than through their desktop or personal computers.

In the developing world, the majority of users are going online for the first time using a smartphone.

"The new paradigm is mobile computing and mobility," David B Yoffie, a professor at Harvard Business School, told the New York Times.

"That has the potential to change the economics of the internet business and to redistribute profits yet again."

BBC.co.uk