Relations between broadcaster Channel 4 and production group Endemol Shine have almost broken down over the right to broadcast Charlie Brooker’s show Black Mirror in the UK.

The acclaimed Channel 4 drama, which began life in 2011 with an episode which featured a fictional prime minister having sex with a pig, was snapped up by US streaming service Netflix last September in a deal understood to be worth an estimated $40m.

Under the deal, Channel 4 believed it still had a “first-look option” to broadcast the drama produced by Endemol Shine in the UK. Although negotiations are ongoing, this right does not appear guaranteed by Endemol Shine, which is owned by Rupert Murdoch’s 21st Century Fox and Apollo Global Management.

The state-owned commercially funded Channel 4 has invested millions in both on and off air marketing for several Shine-Endemol shows including Black Mirror and two of its biggest hits, The Island and Hunted, over the past few years.

Last year’s merger of Endemol and the Fox-owned Shine created one of the world’s largest programme-making and content businesses. As well as Black Mirror, the Island and the Hunted, which are both returning to Channel 4 this year, Endemol Shine produce C4 hits Deal or No Deal and Eight Out of 10 Cats.

Yet over the past 15 months, nine senior executives have left the merged group including Shine Group chief executive Alex Mahon, Just Spee and Tim Hincks, formerly Endemol chief executive and chief creative boss respectively. This exodus has raised questions about who is leading discussions on the development of future projects with important clients such as Channel 4.

Jay Hunt, Channel 4’s chief creative officer, fired off an email to her senior team asking which Endemol Shine shows were currently in production. However, the company denied rumours that it had suspended work with the mega indie.

Hunt said: “Some of our biggest shows are with Shine Endemol. We haven’t suspended working with them.”

A spokesman for Endemol Shine declined to comment, adding: “We are still in discussions with Channel 4 around Black Mirror in the UK, to comment on these would be commercially sensitive.”

Channel 4 commissioned the first ever series of the show described as a Twilight Zone for the digital age and went on to air two, three-part series of Black Mirror along with last year’s 75-minute festive special starring Jon Hamm, Rafe Spall and Oona Chaplin. White Christmas was watched by a total audience of nearly 2 million viewers when it aired last December.

Black Mirror won best TV movie/mini-series at the International Emmy awards in November 2012, just a year after being launched on Channel 4.

The tension over the future of Black Mirror in the UK underlines Channel 4’s complaints about the competitive threat from US-owned companies. In a speech in 2014 chief executive David Abraham said that public service broadcasters were the only bulwark against a broadcasting industry dominated by US media moguls such as Rupert Murdoch and Virgin Media owner John Malone as well as larger technology firms.

Endemol Shine chief executive Sophie Turner-Laing, who formerly reported to James Murdoch at the satellite company Sky, has appointed Peter Salmon, the BBC’s director of studios, who will start in May.