CBS Corporation, the media giant, has bought Last.fm, the social-networking and music site, for $280 million, it announced today.

The cash acquisition by CBS, the US television and radio group, puts an end to months of speculation over possible buyers for the London-based online radio site, which has 20 million active users in more than 200 countries.

The hybrid social networking and music site, which creates automatic playlists for members based on their musical tastes, is understood to have attracted interest from Viacom, the owner of MTV and former parent company of CBS, earlier this year.

The $280 million paid by CBS is lower than previous estimates that had valued the company at $450 million.

Last.fm gives users access to more than three million music tracks through partnerships with major music groups EMI and Warner Music as well as independent aggregators The Orchard and IODA. More than 100,000 independent musicians and 20,000 labels upload their music directly onto the site.

Leslie Moonves, the president and CEO of CBS, said: “Last.fm is one of the most well-established, fastest growing online community networks out there… Their demographics play perfectly to CBS’s goal to attract younger viewers and listeners across our businesses.”

The purchase follows similar online investments by the multi-media conglomerate, including the acquisition of Wallstrip.com and stakes in Joost and Spot Runner.

The takeover comes as Last.fm, founded in 2002, is expanding rapidly into new areas. Last month, it emerged as a competitor to MTV.com, after launching a new music video streaming service. The group is also believed to be in talks with Channel 4 to create a worldwide music chart using software that can track the popularity of songs to rival the UK’s top 40 countdown.

Last.fm is considered a competitor for traditional radio because playlists are tailored to members’ tastes and there are no advertisement breaks.

The site’s founders , Felix Miller, Martin Siksel and Richard Jones, will remain in charge.

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