Facebook has reversed a policy of barring gruesome execution videos, such as decapitations, that it implemented earlier this year, but only under the condition that users denounce them. In May, the company banned such videos, citing concerns over long-term psychological damage.

Monday’s decision drew widespread criticism, including from British prime minister David Cameron, who called it “irresponsible of Facebook to post beheading videos, especially without a warning.” Several support group of victims of violence and kidnappings also criticized the decision.

“We know first-hand the acute distress these videos and images cause and we stress that this continues to be a source of worry to the families of today’s hostages,” Hostage UK told the BBC. Another group said the decision “crossed the line.”

The company initially said such videos will only be allowed if users condemn the violent acts, rather than condone or celebrate them. Amid the criticism, Facebook announced on Tuesday that it will put warning messages before videos to alert users of “extremely graphic content [that] may be upsetting.”

“It’s a step forward, but it’s still horrific content,” said the head of one Internet-safety group of the warning.