Sky has warned that plans by the BBC, ITV and Channel 4 to build a British Netflix could fall foul of the competition regulator.

Stephen van Rooyen, chief executive of UK and Ireland operations at the pay-TV company, said public service broadcasters still accounted for the lion’s share of TV viewing and that any new venture would likely be investigated by the Competition and Markets Authority.

“You [would] have the full might of the public service broadcasters collaborating together. That must – they still command 73% to 74% of viewing share – open up a competition question. It would be subject I would have thought, as it was 10 years ago, to a competition review.”

Carolyn McCall, chief executive of ITV, has said that the protracted talks between the public service broadcasters represent the last chance to create a credible domestic streaming rival to Netflix. More than 10 years ago the BBC, Channel 4 and ITV got together to build video-on-demand service, named Kangaroo, but that was ultimately blocked by the competition regulator.

Despite the Sky warning, the idea of a British Netflix has received regulatory backing. On Wednesday, Sharon White, head of the media regulator Ofcom, again urged the UK’s PSBs to get together and build a British Netflix.

“If the growth of Netflix and Amazon tells us one thing it is that viewers will flock to single destinations that offer a wide variety of quality content,” she said. “A common platform could combine the pulling power of Broadchurch, Blue Planet and Bake Off.”