An advocacy group the Open Source Consortium (OSC) has threatened to take BBC to the European Commission over claims the institution is forcing people to use Microsoft's operating systems. The charge concerns the use of Microsoft technology in the corporation's forthcoming iPlayer due to launch later this year. The planned online service will allow viewers to watch shows up to 30 days after broadcast, but like Channel 4’s 4oD will not be Mac compatible.

A statement from the BBC read: "The BBC aims to make its content as widely available as possible and has always taken a platform agnostic approach to its internet services. It is not possible to put an exact timeframe on when BBC iPlayer will be available for Mac users. However, we are working to ensure this happens as soon as possible and the BBC Trust will be monitoring progress on a six monthly basis."

The OSC claim those wanting to watch the catch-up TV service will be forced to use or buy a PC, initially at least, giving Microsoft an unfair and uncompetitive advantage. "The BBC has a mandate to provide equal access to people irrespective of platform," said Mark Taylor, president of OSC."We don't think it is appropriate to lock people into a particular desktop technology. We believe the BBC has a higher duty of care than a purely commercial organisation.”

The group, composed of organisations, businesses and individual proponents of open source software, has already complained to the telecoms and broadcast regulator Ofcom, as well as the DTI and BBC Trust. Ofcom have previously stated that access to the iPlayer be "only one of many factors influencing the decision to purchase a new computer operating system. However the OSC disagrees and says the next step is to make a formal complaint to the European Commission. "We're preparing the full details at the moment and we will be sending a formal letter within the next week," added Mr Taylor.