A safety adviser for Facebook has called on the social network to rethink how it deals with images of gruesome executions and injuries.
The news comes in the wake of several grim beheadings in Syria by Islamic State militants, including that of American journalist James Foley.
Facebook had initially refused to delete the pictures, but later blocked the images.
Last year Facebook clarified its policy on graphic content, after a video of a woman being beheaded in Mexico appeared to go viral on its site.
After a review, Facebook said that while it wanted to help people share experiences and raise awareness, it had to balance those impulses with the needs of its other users:
"Facebook has long been a place where people turn to share their experiences and raise awareness about issues important to them. Sometimes, those experiences and issues involve graphic content that is of public interest or concern, such as human rights abuses or acts of terrorism. In many instances, when people share this type of content, it is to condemn it. However, graphic images shared for sadistic effect or to celebrate or glorify violence have no place on our site.
When people share any content, we expect that they will share in a responsible manner. That includes choosing carefully the audience for the content. For graphic videos, people should warn their audience about the nature of the content in the video so that their audience can make an informed choice about whether to watch it."
But after the latest killings, Stephen Balkam, chief executive of the US's Family Online Safety Institute and a member of the Facebook Safety Advisory Board, said he wanted to see another rethink.
"There may be instances in which graphic photos and videos, like the beheadings in Syria, can be justified as being in the public interest," he said in an interview with the BBC.
"However, if they are hosted on Facebook or other social media platforms, there should be two barriers put in place. First, an interstitial, or cover page over the graphic images. With an interstitial in place, a user, particularly a child, will not have the image appear in their timeline or be easily seen if they are sent a link to the images.
"Secondly, there should be an age gate, saying that you must verify that you are 18 years of age. While this is easily circumvented, it does at least warn the user and may well deter both kids and adults alike."
Facebook maintains that its community standards aim to protect both sensitive users and free speech, but that it would listen to feedback.