AT&T, the biggest U.S. telecommunications group, will launch an internet TV service that allows its subscribers to view a selection of live and streamed TV channels - as they are broadcasting - on their PCs (over any wired or wireless broadband connection) for $20 a month, writes the Financial Times.

The browser-based service - AT&T Broadband - will be the first of its kind in the U.S. The carrier has teamed with MobiTV, a fast-growing mobile TV content aggregator, to deliver the service. AT&T Broadband will initially offer some 20 channels, including the History Channel, the Weather Channel, the Food Network, Bloomberg and Oxygen, according to the Associated Press.

Viewers will see whatever commercials are being shown on the live broadcast, but no advertisements are planned for the browser window and control panel that frame the TV picture.

The launch comes amid an explosion of internet-based video content services, including user-generated video sites such as YouTube and Google Video, and TV and movie download services, including Amazon's just-launched Unbox.