Social media platform Twitter is cracking down on hate speech. Illustration: Kacper Pempel / Reuters.

Twitter accounts belonging to certain Neo-Nazi, white supremacist and black nationalist groups were suddenly unavailable on Tuesday after the social media platform introduced new rules to combat hateful speech and conduct.

The Center on Extremism — a project of the Anti-Defamation League (ADL) — reported that a number of accounts belonging to racist and extremist groups had been banned. Twitter feeds belonging to the American Nazi Party, the League of the South, Vanguard America and the New Black Panther Party for Self Defense were among those closed for business on Tuesday.

“ADL commends Twitter for taking these significant steps to tackle hate on their platform,” the anti-bias organization’s CEO, Jonathan Greenblatt , said in a statement. “We long urged Twitter to push back against hateful and violent rhetoric, and these latest actions are encouraging.”

Twitter’s guidelines on “Hateful Conduct” forbid users from promoting violence on the basis of race, ethnicity, religious affiliation and sexual orientation. The platform will no longer “allow accounts whose primary purpose is inciting harm towards others on the basis of these categories,” the company said.

Online behavior that will not be tolerated under the new guidelines include “violent threats; wishes for the physical harm, death, or disease of individuals or groups; references to mass murder, violent events, or specific means of violence in which/with which such groups have been the primary targets or victims; behavior that incites fear about a protected group; repeated and/or or non-consensual slurs, epithets, racist and sexist tropes, or other content that degrades someone.”

Under these rules, Twitter users who incite the murder of Jews, or who attack or mock the State of Israel by comparing its actions with those of the Nazis — to cite just two of the antisemitic memes that appear frequently in social media — face a potential ban. Additionally, racist imagery, such as the Nazi swastika, will be hidden from view.

A spokeswoman for Twitter told the BBC on Tuesday that the new rules would “reduce the amount of abusive behavior and hateful conduct” on the network.

“If an account’s profile information includes a violent threat or multiple slurs, epithets, racist or sexist tropes, incites fear, or reduces someone to less than human, it will be permanently suspended,” she explained.

“We plan to develop internal tools to help us identify violating accounts to supplement user reports,” the spokeswoman added.