The protest has the support of over 250 artists and organisations that signed the open letter, from Planned Parenthood to the Writers Guild.

Director of Programs at NCAC, Svetlana Mintcheva, said: “We recognise that moderating content for billions of users is challenging and draw the line between art and images that are not art is hard. Yet, if Facebook and Instagram want to be platforms for artists, they need to modify their current overbroad ban on photographic nudity, which harms artists who work with the human body, especially those exploring issues of gender and identity. We urge the company to adopt an art-friendly policy developed with the help of a group of global stakeholders, such as arts advocates, historians, curators and artists.”

The NCAC has written an open letter to the social media sites – the proposal outlines working with art advocate stakeholders, as done by YouTube over a decade ago, to become more artist-friendly.

“The work I’m allowed to post is fundamentally different from the work I make,” Tunick said in a statement. “To me, every pixelated nipple only succeeds in sexualizing the censored work. As a 21st century artist, I rely on Instagram. It’s the world’s magazine and to be censored on it breaks my spirit.”

Andy Cohen, Andres Serrano, actor-photographer Adam Goldberg, Red Hot Chili Peppers drummer Chad Smith, artist Paul Mpagi Sepuya, and Tunick himself donated images of their nipples which the participants used to cover their own body parts, highlighting the inequality and sexualisation of women’s bodies in particular in the existing nudity policies.

The campaign hopes to influence a change in the policies of Facebook and Instagram, and create new guidelines that protect the work of artists who make photographic artist nudity, rather than censoring them completely.

The protest was organised by artist Spencer Tunick , in collaboration with the National Coalition Against Censorship. Tunick, an artist who has been creating influential nude photographs for over a decade, captured the protest as part of the #WeTheNipple campaign.

125 people stripped naked in a demonstration outside Facebook and Instagram’s New York headquarters, challenging social media censorship of artistic nudity. On a crisp Sunday morning (June 1), the nude protesters lay down on the road, covering their genitals with large images of male nipples.

Instagram’s community guidelines currently ban naked pictures. “We know that there are times when people might want to share nude images that are artistic or creative in nature, but for a variety of reasons, we don't allow nudity on Instagram.""This includes photos, videos, and some digitally-created content that show sexual intercourse, genitals, and close-ups of fully-nude buttocks. It also includes some photos of female nipples, but photos of post-mastectomy scarring and women actively breastfeeding are allowed”.

Facebook’s crack down on “the display of nudity or sexual activity because some people in our community may be sensitive to this type of content.” Its community standards read: “Our nudity policies have become more nuanced over time. We understand that nudity can be shared for a variety of reasons, including as a form of protest, to raise awareness about a cause, or for educational or medical reasons. Where such intent is clear, we make allowances for the content.”

Tunick has been photographing mass nude photo stunts for almost three decades in public places around the world. His more recent shoot in Melbourne, Australia saw 500 people photographed naked on a car park roof. “There is no reason for Facebook or Instagram to censor this video or block from hashtags,” he said in a video from Sunday’s protest.

Women’s group Grab Them By the Ballot founder Dawn Robertson, who participated in the action, told CNN that her personal account had been banned six times for posting artistic images of naked women, and the group’s ad account was disabled by Facebook for posting a nude painting. She told CNN that the guidelines were utilized inconsistently by both Facebook and Instagram: “It's like playing Russian Roulette. I never know, when I post, whether they're going to take it down.”

“Facebook is dictating how the world views the female nude body, and they’re treating it like it’s a crime and it's shameful. Something has to be done. They have way more power than they should.”

Read NCAC’s letter to Facebook and Instagram below:

”Dear Ms. Bickert,

Instagram and Facebook have dramatically increased artists’ ability to reach audiences and have opened new possibilities for artistic exploration and expression. Artists who lack access to traditional distribution channels can reach global viewers as never before. Museums and art institutions are able to broaden access to their collections and promote exhibitions on an unprecedented scale.

Yet Facebook and Instagram, while permitting nudity in sculpture and painting, ban photographic representations of the nude body. The nudity ban is punishing for photographers and particularly harms artists whose work focuses on their own bodies, including queer and gender nonconforming artists. It also affects museums and galleries that have difficulty promoting photography exhibitions featuring nudes.

Facebook has the legal right to impose content restrictions. Yet, as a company with over two billion users, and one billion on Instagram, Facebook’s actions impact culture on a global scale. The company’s extraordinary expansion and success has made it a worldwide power serving a large diversity of communities with different, and often conflicting, values and beliefs.

We acknowledge that moderating content for billions of users with diverse values presents unprecedented challenges and that drawing the line between art and images that are not art is notoriously hard. But this challenge does not justify banning all photographic images of the nude body, a ban that imposes the beliefs of some Facebook users on the entire world, stifles artistic expression, and enforces gender discrimination by permitting images of male nipples while prohibiting female nipples.

Over twenty US and international arts and free speech organizations and hundreds of artists have joined us in urging Facebook and Instagram to become welcoming platforms for the arts (ncac.org/we-the-nipple). There are many possible solutions to the challenges of serving diverse communities, including allowing individuals the ability to block all nudity and creating filters to screen nudes that may appear unexpectedly in users’ feeds. Such mechanisms would allow user control, rather than forcing Facebook to judge what content is permissible.

As a commitment to changing its policy on photographic nudity, we propose that Facebook convene a group of globally representative stakeholders including artists, art educators, museum curators, activists, as well as Facebook employees, to develop guidelines that transparently balance the competing interests of the many different communities Facebook serves.

By engaging with relevant stakeholders who share a commitment to change, Facebook and Instagram can implement a policy that recognizes the value of one of their core communities: creative artists.”