On Tuesday, Google launched its first mobile phone in the United States in conjunction with the German-owned carrier T- Mobile.

The new device, called the T-Mobile G1, functions on 3G and wi-fi networks and is specially designed to offer high-speed access to popular Google services such as search, Gmail, Google maps with directions and YouTube.

It features a touch screen and a slide-out Qwerty keyboard, a feature that could give it an advantage over the iPhone. The phone also offers a 3-megapixel camera.

Cole Brodman, chief technology officer of T-Mobile USA, said the device was designed to bring the mobile internet to the masses. "The mobile internet experience hasn't been compelling. We're going to change that."

A mobile version of Amazon's MP3 store will be preloaded onto the G1, which will allow users to search, download, buy and play music directly from the popular music store.

The G1 will support the Android Market, a mobile application in which third party developers can offer additional programmes for the device, which is manufactured by Taiwanese electronics maker HTC.

It features the Android operating system, developed by Google engineers over the last three years. Android is an open source system than can be used and changed by any device manufacturer.

To help develop Android, Google also formed the Open Handset Alliance - a partnership of more than 30 firms to make phone software easier to work with.

The group includes operators such as Telefonica, handset makers such as HTC and Motorola, as well as chip makers such as Intel and Qualcomm. Many of the partners demonstrated early prototype Android phones at the Mobile World Congress held in Barcelona in mid- February.

Google, which currently dominates advertising on the internet, hopes that Android will become the standard operating system for increasingly sophisticated mobile phones, which experts believe will provide the main access to the internet for billions of people without computers.

The G1 is priced at 179 dollars, 20 dollars less than the iPhone, and will be available from October 22. Buyers must commit to a two- year contract.

The G1's data plans are also far less than those available for the iPhone in the US, with an unlimited text and internet plan costing just 35 dollars, in addition to regular voice plans. A plan that allows unlimited internet access but places limits on text messaging costs 25 dollars.

The G1 will be available in the UK in November and across Europe in the first quarter of 2009.