Fifteen minutes into her shoot with model Nyome Nicholas-Williams, photographer Alexandra Cameron knew she had captured the perfect image: a dreamy split second with Nicholas-Williams bathed under natural light, her eyes closed and arms wrapped around her breasts.

The response on Instagram was ecstatic: “stunning … beautiful … this should be in a gallery!”. But within hours, Instagram had deleted the photo and Nicholas-Williams had been warned her account could be shut down.

“Millions of pictures of very naked, skinny white women can be found on Instagram every day,” said Nicholas-Williams. “But a fat black woman celebrating her body is banned? It was shocking to me. I feel like I’m being silenced.”

Her followers rallied. Hundreds of users fought the platform last week to share the censored photos of Nicholas-Williams under the hashtag #IwanttoseeNyome, while Cameron accused Instagram of a disconnect between its positive statements over Black Lives Matter and the apparent unfair targeting of its black content creators.

The platform, with over a billion users and 15,000 people working around the world to review posts and look for banned material, has been repeatedly accused of discriminating against black people.

In June CEO Adam Mosseri acknowledged the need for Instagram to look at “algorithmic bias” and said that he was “hearing concerns about whether we suppress black voices and whether our products and policies treat everyone equally”.

In a blogpost he wrote: “Words are not enough. That’s why we’re committed to looking at the ways our policies, tools and processes impact black people and other under-represented groups on Instagram.”

A month later, Vishal Shah, the company’s vice-president of product, announced that an internal equity team would be rooting out “any bias in our systems and policies”, and the platform launched its #ShareBlackStories campaign to promote black voices.

Cameron, 34, who has worked as a photographer for more than a decade and posted thousands of photos on her account, was furious at the apparent discrepancy between what Instagram said and what it was actually doing.

She said: “I have posted photos of many more women – white women – who had [fewer] clothes on than Nyome that never got reported or deleted. This was the first time it happened to me, and it kept happening because I kept reposting the pictures and they kept getting deleted, and you have to ask why.

“What is it about a plus-size black woman’s body that is so offensive and so sexualised? The Playboy feed is filled with naked white models and it’s all for the male gaze, which is the opposite of what I do, and they’re allowed to stay.”

Under the platform’s community guidelines, nudity or sexual activity is restricted but is monitored on a case by case basis. Female nipples, unlike male ones, have long been banned and photographers have used inventive ways to craftily cover them up, using everything from leaves, emojis, black censorship blocks and often, as in Cameron’s case, the model’s arms or a sprig of lavender.

“Ironically, it was supposed to be a confidence shoot,” said Cameron, describing the style of shoots she does specifically to boost female self-esteem. “Where is Nyome’s confidence level supposed to be now?”

Nicholas-Williams, 28, who has modelled for Adidas, Boots and Dove, said that she had struggled with an eating disorder as a teenager and had worked hard at loving her own body. “It’s a process, but I’m unapologetic now and I want to promote self-love and inclusivity because that’s how I feel and how I want other women like me to feel,” she said.

“It does make a difference to be out there as a fat, black woman and be proud. More black women have been getting in touch with me to say the same has happened to them. So I know I’m not alone.”

Gina Martin, the writer who successfully campaigned to change the law in 2018 to make upskirting a criminal offence, took up Nicholas-Williams’s cause with Instagram. By last Friday, Nicholas-Williams and Cameron had all of their original posts from the shoot reinstated.

“When people exist in bigger bodies, and black women and people of colour talk about this censorship, the response is just ‘oh yeah, that happens’,” said Martin.

“It’s embarrassing that it takes a verified white woman to talk about it for Instagram to do something. And this is just one case. It’s been happening for years.”

Instagram was approached for comment but had not responded at the time of writing.