Alek Minassian, 25, appeared in court on Tuesday, a day after a rental van struck pedestrians in the city, killing 10 and injuring 15.

Facebook confirmed to the BBC that Minassian was the author of a post which read in part: "The Incel Rebellion has already begun! We will overthrow all the Chads and Stacys! All hail the Supreme Gentleman Elliot Rodger!" The post also contained a reference to the message board 4chan.

"Incel" is short for "involuntarily celibate" and in particular refers to online groups of men who feel that they can't enter into sexual relationships.

The attitudes of men who visit the boards vary widely, but online they frequently vent anger against sexually prolific men ("Chads") and women ("Stacys"). More generally, incel forums often include rants aimed at feminism and women.

In November, Reddit banned a section or subreddit of its site devoted to incels for hosting violent content.

On Tuesday, another subreddit dedicated to incels, r/Malecel, was banned.

However, other similar boards remain active on Reddit, and many other sites play host to incel discussions.