Microsoft has claimed around a million new PCs in the UK each year are sold with counterfeit or pirated copies of its software.

At the start of the 'Keep IT Real' campaign, a three-year drive to cut piracy by five per cent, Microsoft said that it estimated two-thirds of the estimated 1.5 million computers built and sold to consumers and small businesses by local retailers do not have genuine licensed copies of Microsoft software. This software includes Windows XP as well as other Microsoft applications such as Office.

Microsoft said that while there are cowboys out there who knowingly practice hard disk loading – where either fake copies or more copies of the software than have been licensed are loaded onto hard drives – or who sell consumers fake copies of software, many retailers themselves are victims of the counterfeiters.

"It is a huge problem for them as they don't have the same trusted sources that large original equipment manufacturers use," explained Alistair Baker, managing director of Microsoft UK.

To help these traders and to stop the rogue retailers, Microsoft will step up its Feet on the Street programme where teams of investigators are sent to check software licences at businesses in towns around the UK.

Acting on tip-offs, these investigators will visit over 800 UK companies it suspects of piracy as well as swooping on towns such as Middlesbrough and Glasgow which are considered piracy hotspots. The company will also continue to monitor auction sites such as eBay which are full of traders selling pirated and counterfeit software.