Microsoft is set to form an assault on video-sharing websites, including the hugely successful YouTube.com by launching a new service that will allow users to post their own web content, Times Online has learnt.

The Microsoft site will launch this summer as the world’s largest software developer moves to increase the reach of its MSN portal by tapping the explosive growth of social networking sites such as MySpace.com.

It will target users ranging from amateur documentary makers to aspiring pop stars and will earn revenues through advertising. Microsoft, which recently offered clips of World Cup coverage, is also planning to offer more conventional video content in areas such as comedy and extreme sports.

Details of the new service, which will be rolled out simultaneously in several territories, are yet to be finalised. However, a Microsoft executive told Times Online that the company is planning to launch a viral advertising campaign to publicise it "imminently".

YouTube, which offers its users the chance to "broadcast themselves", has been branded "the internet's latest instant phenomenon" in Silicon Valley. More than 80 million videos are viewed on the site every day, ranging from teenage confessionals to video diaries recorded by troops in Iraq.

The push to compete with the 18-month-old start-up signals how Microsoft is being forced to revisit its net strategy.

MSN made a push into original content in the 1990s but later scaled back its involvement, selling Slate, the online magazine in 2003 and disposing of a controlling stake in the MSNBC cable channel last year.

Microsoft now plans to plough back into the field by offering more professional content and plans to reshape viewers’ online viewing habits. In a challenge to traditional broadcasters such as the BBC and ITV, it is exploring ways to move viewers away from short internet clips to longer-format television-style online programmes.

The entry into user-generated content is designed to tap into the explosive popularity of sites that offer the public the chance to post their own video and audio content online.

Along with community sites such as MySpace, which is owned by News Corporation, parent company of Times Online, YouTube is part of the so-called "web 2.0" generation - sites that aim to give users an online space to create and share content.

This week Hitwise, the online research company, said that MySpace has overtaken Yahoo’s e-mail log-in page as the single most-visited web destination in America, accounting for 4.5 per cent of all US internet visits.

Microsoft is under pressure to show it can harness the same traffic flows. It has set aside $2 billion to fund its rivalry with groups ranging from YouTube to Google, chiefly through its next generation of web-based Windows Live services.

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