Facebook has moved to defend and clarify its policies on gender-based hate speech amid pressure from advertisers.

The company said there was “no place” on the social network for content that was threatening, incited violence or was “deemed to be genuinely or directly harmful”, but that “distasteful content on its own” does not violate its policies.

The company was responding to an open letter written by a coalition of more than 60 groups, in which they asked Facebook users to pressure companies to pull their advertising from Facebook until it removes offensive pages and changes its policies on moderating content that targets women for violence.

Nissan UK indicated on Twitter that it had spoken to Facebook about the pages and pulled ads as a result of the campaign, while other advertisers including Finnair and Ocado have also acknowledged discomfort with the placing of their ads on particular pages, after tweets were sent to them on the matter.

The open letter, written by representatives of groups including Women, Action & Media, the Everyday Sexism Project and End Violence Against Women, lists examples of Facebook pages such as Fly Kicking Sluts in the Uterus, Kicking Your Girlfriend in the Fanny because She Won't Make you a Sandwich and Violently Raping Your Friend Just for Laughs.

Facebook said it tried “to make it very easy for people to report questionable content” on the site. The particular pages mentioned in the letter have now been removed.

The campaigners say Facebook has “long allowed content endorsing violence against women”. They argue that such pages and images of beaten and bloodied women with slogans such as “next time: don’t get pregnant” and “this bitch didn’t know when to shut up” often survive the reporting and moderation process, sometimes on the basis that they constitute humour.

“These pages and images are approved by your moderators, while you regularly remove content such as pictures of women breastfeeding, women post-mastectomy and artistic representations of women’s bodies,” they write.

Facebook said some “vulgar and offensive” content will remain on the site on the basis that it is free speech, not hate speech.

“As you may expect in any diverse community of more than a billion people, we occasionally see people post distasteful or disturbing content, or make crude attempts at humour. While it may be vulgar and offensive, distasteful content on its own does not violate our policies.”

The company said it requires that distasteful and disturbing pages “to be clearly marked” as such. “In many instances, we may also require a page administrator to display their real name on the page, or the page will be removed.”

The campaigners say Facebook’s moderators remove content that is “violently racist, homophobic, Islamophobic, and anti-Semitic” on a daily basis. “Your refusal to similarly address gender-based hate speech marginalises girls and women, sidelines our experiences and concerns, and contributes to violence against them.”

The letter asks Facebook to recognise content that trivialises or glorifies violence against girls and women as hate speech. It also asks Facebook to train moderators to recognise and remove such hate speech and understand how online harassment interacts with real-world violence against women.