MySpace, the web’s largest social network, will tomorrow launch a rival to YouTube, the video-sharing site owned by Google.

The decision to launch MySpace TV, where users will be able to upload and view video clips, comes despite MySpace holding a $900 million advertising deal with Google and underscores the complex mesh of relationships that span the internet’s largest companies.

The move comes as MySpace, which has about 110 million users, faces fierce competition from rivals such as Facebook and Bebo.

According to Comscore, the market analysts, the number of visits to Facebook’s increased by 89 per cent last year, compared with 34 per cent at MySpace.

MySpace is owned by News Corporation, parent company of Times Online.

MySpace has already struck deals with a string of content groups for “branded channels” that will appear on MySpaceTV.

Partners include National Geographic, The New York Times and Reuters. The service plans to make money through advertising and will be launched in 15 countries and in seven languages.

YouTube recently launched local sites in nine different countries in a bid to extend its global reach.

The new site will operate as a stand-alone destination – myspacetv.com – and will initially be launched as a beta, or test, platform.

The rolling addition of new features to keep viewers engaged may prove a constant feature of the sector, recent analysis suggests.

A recent report by Park Associates, the analysts, found that users of social networking sites are “chronically unfaithful” with nearly half regularly using more than one site and one in six using three or more.

The findings underscored the problems faced by social networks in keeping young flighty users engaged in a market where the majority of services are free to join and use.

Last month, Facebook launched a new "platform" that allows outside developers to create online services, such as photo slideshows and online data storage, which can be operated from inside its site.

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