Twitter has announced it will actively remove graphic images of the beheading of American journalist James Foley by IS militants.
The social network's CEO Dick Costolo said that it would suspend accounts as soon as they post graphic imagery of the killing.
The decision follows a wider crackdown on violent or graphic images of dead or dying people on the site.
The service said that it would consider removing images "from when critical injury occurs to the moments before or after death" on the request of family members.
Twitter’s vice president of trust and safety Del Harvey said:
"We will not tolerate abuse of this nature on Twitter.
"We have suspended a number of accounts related to this issue for violating our rules and we are in the process of evaluating how we can further improve our policies to better handle tragic situations like this one.
"This includes expanding our policies regarding self-harm and private information, and improving support for family members of deceased users."
But others have suggested that the decision could affect how news is covered - and called on Twitter not to pro-actively delete images, or set a precedent that could not be enforced.
Google's former public policy chief Andrew McLaughlin told the Washington Post that "the photos are obviously newsworthy"
"It's awful that these photos were taken, and it's awful that this moment happened, but their very existence is news."
A wider attempt not to post images and video of the slaying has also gone viral on the social network, under the hashtag #ISISMediaBlackout.