Ofcom, the media regulator, is facing new pressure to use its powers to force the BBC to increase the diversity of its workforce after the corporation published the pay of its top stars last week.

Submissions to Ofcom, part of a consultation into how it will regulate the BBC, call on the body to introduce diversity targets for the number of BAME (black, Asian and minority ethnic) staff working behind the scenes.

The diversity of the BBC is being heavily scrutinised after the corporation published a list of its top earners that revealed a huge gender pay gap and that the 10 highest-paid BAME stars collectively received around the same as Chris Evans last year.

Before the publication of the list Sir Lenny Henry, the comedian, criticised Ofcom and the BBC for not doing enough to tackle diversity. The BBC says about 14% of its staff are from a BAME background, but Henry claimed the number of BAME people responsible for making programmes is “probably closer to 1.5%”, adding: “This is the dirty secret of what our industry really looks like behind the camera.”

Ofcom became the first independent regulator of the BBC earlier this year and has published a draft operating licence that outlines how it plans to monitor the corporation.

A consultation into the draft operating licence closed last week, with the National Union of Journalists, Directors UK, the Campaign for Broadcasting Equality, and the charity Stonewall among the groups calling on Ofcom to do more to improve diversity at the BBC.

The NUJ said it “strongly challenges” Ofcom’s decision not to include a requirement for the BBC to improve the diversity of its off-screen workforce. Its submission also called for Ofcom to demand that the BBC produce data on the diversity of all staff and freelances providing programming and services, and for the media watchdog to collect its own figures on the gender pay gap at the broadcaster.

The NUJ said there needed to be a “sea-change in culture” at the BBC, adding: “If the people who are doing the hiring and the commissioning continue to be predominantly Oxbridge, white males, there is little hope that the aim of having BAME representatives on-screen and off-screen will be achieved.

“It is clear that while there are attempts to consider diversity issues, Ofcom does not go far enough to ensure that change is a reality, rather than a statistic.”

Directors UK, which represents film and TV directors, said: “By not formally incorporating workforce diversity into the performance measures just as most of the rest of the industry is supporting or adopting new data measurement in this field, Ofcom is in danger of undermining the importance of the issue and appearing to be alarmingly out of touch or indifferent.

“We have evidence from our own members that the off-screen environment does directly influence the diversity of the on-screen content, stories and perspectives shown.

“Television remains a closed, exclusive sector that is overwhelmingly white, male and middle class, and the BBC’s pursuit of its public purposes and high-level objectives presents a structured and comprehensive opportunity to positively impact this situation.”

Stonewall, the LGBT rights charity said in its submission to Ofcom that it would “strongly encourage consideration of off-screen diversity when holding the BBC to account”.

It added: “Portrayal and representation that is fair, accurate and authentic is much more likely to come from an off-screen workforce that is as diverse as the communities it is duty-bound to represent.”

The BBC has said it is aiming for half of its presenters to be women and for the gender pay gap to be closed by 2020. It also wants 15% of staff to come from a BAME background by the same year.

A spokesperson for the BBC said: “The BBC already has one of the most diverse workforces in the UK – more diverse than the civil service and more diverse than any FTSE100 company that reports its figures. But the targets we have set ourselves to reach by 2020 are among the most ambitious and stretching of any organisation because it’s right that we represent and reflect the whole of the UK today.”

Ofcom proposed in its draft operating licence that the BBC will report annually on how it has reflected, represented and served the diverse communities of the UK. It also called on the BBC to draw up a diversity code of practice that explains how the corporation will commission programmes that authentically portray the population.

An Ofcom spokesperson said: “Our consultation is now closed and we will carefully consider all feedback before we finalise our rules.”