Sony has launched its digital music distribution service Connect in the US.

The service offers music buyers the facility to acquire music online in a format that's only compatible with Sony portable devices. The company also announced an initiative with United Airlines under which frequent fliers will be able to exchange air miles for tunes.

Executive vice president and chief financial officer Sony Corporation of America Robert Wiesenthal said: "Sony Connect provides consumers with an easy-to-use store that is integrated with a wide range of devices, while meeting the requirements from the music industry for secure distribution of digital content."

Sony Connect launches with a catalogue of 500,000 tracks form all the majors and many independent labels. Tracks are available on an à la carte basis at 99 cents each, with album prices set at $9.99.

The service also allows users to play their downloads as many times as they like on up to three registered PCs, and unlimited personal devices. Users can also burn up to ten CDs.

The company also launched its family of Hi-MD Walkman digital music players. The company hopes to leverage the two and a half million Walkman-branded devices it has already sold in the US to help it establish some market share in the competitive industry, which is currently dominated by Apple's iTunes Music Store.

"In the coming months, consumers will be treated to a steady stream of upgrades. Sony Connect plans to roll out newer versions of the software, providing users with more features and flexibility, and compatibility with devices from other manufacturers", the company said.

Sony VP marketing for portable audio products Todd Schrader said the company was "aggressively looking into a hard drive device", a device Forbes describes as a potential iPod killer.

Inside Digital media analyst Phil Leigh told Forbes: "Sony is a very strong brand and it's likely to be a real contender in the market, but what will determine their success is whether they unveil a device to compete with iPod."