Internet service provider Sky has become the latest telecoms firm to voice concerns about the YouView IPTV project.
The firm submitted a late complaint to Ofcom about the broadband-enabled TV initiative - which involves several broadcasters, plus TalkTalk and BT - ahead of the regulator's board meeting on Tuesday.
In doing so, it joined a growing band of dissenters, which includes rival ISP and subscription TV provider Virgin Media.
The Ofcom board was meeting to discuss the concerns raised by other critics of the scheme, originally known as Project Canvas, which aims to set universal standards for set-top IPTV boxes.
Units built upon YouView software are set to hit UK stores as early as next year, providing Ofcom chooses not to intervene.
Defending the project goals, Richard Halton, Chief Executive of YouView, recently claimed it would create competition among TV platforms.
However, Virgin Media's Neil Berkett has argued that the development of universal standards based upon the YouView design risks creating a market monopoly.