Project Canvas, the initiative designed to bring internet TV into the living room, faces further pressure after a fifth complaint emerged, calling for it to be probed by the regulators.
The Open Source Consortium (OSC), a trade body for companies that work in open standards software, has formally written to Ofcom asking it to investigate Canvas, whose backers include the BBC, ITV, Channel 4 and BT.
This follows previous complaints from Virgin Media, United for Local Television, IP Vision and Six TV who believe the partners have too much control over a platform that was designed to be open.
The OSC said in its letter that Canvas will have "adverse consequences for the device and software sector, diminishing consumer choice and causing inevitable consumer harm". Ofcom will announce its verdict next month.