Sir Lenny Henry has attacked "fake diversity" claims by broadcasters that could give a misleading picture of the number of black, Asian and minority ethnic (Bame) people working behind the cameras.
The actor and comedian called on media regulator Ofcom to do more to enforce off-screen diversity in a keynote speech in London on Tuesday.
Pointing out the watchdog sets out minimum requirements for types of programmes, such as children's shows, that broadcasters air, he joked: "We are just asking for the same consideration as Peppa Pig."
Sir Lenny said Bame staff were let down by a "Milli Vanilli" approach by media organisations and their off-screen representation had reached a "crisis level".
He said broadcasters should be urged to ring-fence funds for programming created by Bame employees.
The 58-year-old campaigner said diversity was "not a luxury, but utterly, absolutely and completely essential" with society "increasingly splintered" by issues like Brexit and recent terror attacks.
"All broadcasters now recognise the importance of diversity and for the first time it has been enshrined in the BBC charter... there has definitely been progress and we should be proud of that, but I am sounding the alarm that this progress may all come to nothing," Sir Lenny told the audience at Westminster's Portcullis House.
"Yesterday Ofcom completed a consultation process on how the BBC's performance should be measured... but its headline is fake diversity, 'Milli Vanilli' diversity. It says it will set the BBC target of on-screen diversity but will not set targets for diversity behind the camera."
Quoting a figure from the BBC earlier this year, that 14.5% of its workforce are Bame, Sir Lenny protested that the number takes into account people in roles such as finance and overseas projects, rather than people specifically involved in UK programming.
He continued: "If the pickers and deciders remain the same then nothing changes, because only what gets measured gets done."
Responding to Sir Lenny's comments, an Ofcom spokesman said: "Improving diversity in broadcasting - behind and in front of camera - is a crucial issue and a priority for Ofcom.
"We expect the BBC to increase diversity off-screen, and it has a workforce target of 15% representation of Black, Asian and ethnic minorities, across all staff, including leadership, by 2020. We are clear that we will consider further action if we don't see early and continued progress."
A spokeswoman for the BBC also responded, saying: "14.5% of the BBC's UK-based staff are from black, Asian and minority ethnic backgrounds.
"The figure is even higher in some areas of the organisation, like Network News, and in areas where we have further to go, targeted measures have been put in place to help us reach our 15% target by 2020.
"We have the most stretching targets of any UK broadcaster and will continue to build on our progress in this area."