Tumblr is to launch a new policy banning "self-harm blogs" from the site, with posts promoting anorexia, bulimia and self-mutilation set to be prohibited.

The blogging site had previously allowed blogs which promoted and depicted self-inflicted injury, but in a staff blogpost Tumblr said the policy would be changing "next week".

"Our content policy has not, until now, prohibited blogs that actively promote self-harm," the post read.

"These typically take the form of blogs that glorify or promote anorexia, bulimia, and other eating disorders; self-mutilation; or suicide."

Tumblr said it "strongly opposed" such messages, but had been faced with a dilemma:

The question for us has been whether it's better to (a) prohibit them, as a statement against the very ideas of self-harm that they are advancing, or (b) permit them to stay up, accompanied by a public service warning that directs readers to helplines run by organizations like the National Eating Disorders Association.

The statement said Tumblr would be implementing a new content policy "in the very near future" which would prohibit content "that actively promotes or glorifies self-injury or self-harm".

"This includes content that urges or encourages readers to cut or mutilate themselves; embrace anorexia, bulimia, or other eating disorders; or commit suicide rather than, eg, seek counselling or treatment for depression or other disorders."

The statement added: "Of course, we will allow any affected blogs a grace period in which to edit or download your content" – implying that if offending material was left on an individual's Tumblr account it would eventually be deleted.

In addition, the site will show "'public service announcement'-style language" to users searching for terms typically related to self-harm blogs, directing them to self-help organisations and similar.