More than 100 black and minority ethnic journalists have written to UK editors to denounce a lack of diversity that has led to “a long litany of inadequacies in newsroom coverage of race and how stories about non-white people are covered”.

The journalists, assembled under the auspices of a new group, Black Journalists Collective UK (BJCUK), call on editors to improve diversity among their staff in order to improve their reporting of race issues and subjects.

“We need journalism that better serves all communities in the UK and therefore we need newsrooms that reflect the society they serve,” the letter says. “It is clear there is much more progress to be made, therefore the BJCUK is calling on all newsrooms to urgently show their commitment to improving their reporting of racial issues and subjects, and to increasing the diversity of their staff by signing up to the points outlined in the manifesto below.”

They cite recent media coverage of the singer Jamelia and the footballer Raheem Sterling. Jamelia was widely linked by news reports last weekend to the murder conviction of a Birmingham man. They had described him as her “stepbrother” after it emerged his father had a brief relationship with her mother more than three decades ago.

In an article published bythe Guardian, Jamelia pointed out that the reality TV personality Ferne McCann had received sympathy and opportunities to tell her story after her ex-boyfriend was jailed for an acid attack in a nightclub that injured 14 people. Jamelia, on the other hand, said she had lost work. “I won’t state the obvious here,” she said.

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Writing on Instagram a week earlier after a rival team’s fans had allegedly racially abused him – Sterling accused some sections of the press of helping to fuel racism. He cited a different tone in coverage of the personal lives of black players compared with white players. His comments led to an angry rebuttal from the Sun.

The BJCUK letter says its members “believe there is a direct correlation between the ethnic makeup of the staff in a newsroom and how issues are covered”. It cites 2015 research by the Reuters Institute for the Study of Journalism that found only 0.4% of British journalists are Muslim, and just 0.2% are black.

A study by the National Council for Training Journalists found that while 26% of white candidates were able to secure newsroom jobs six months after graduation, only 8% of their black peers found jobs in the press.

Marverine Cole, a freelance broadcaster and course director of journalism at Birmingham City University, who helped to orchestrate the letter, said it came about after she and BAME peers in the media became frustrated with stories surrounding black public figures in recent weeks.

She told the Voice: “The BJCUK feels very strongly that news organisations need to better handle the career progression of those BAME journalists who are already working hard within their newsrooms. There is a clear issue of people working in fear of speaking out about their disquiet; people unhappy at being paid less than their white counterparts and being continually overlooked for promotion.”