Twitter permanently bans white supremacist David Duke

White supremacist David Duke has been permanently banned from Twitter for violating the platform's rules on hate speech, the company confirmed late Thursday.

Duke's account "has been permanently suspended for Twitter Rules on hateful conduct," a Twitter spokesperson said in a statement. Twitter's policy, revised in March, prohibits posts that promote violence or threats of violence against people based on their religion, race or ethnic origin.

It wasn't immediately clear what specific post or posts by Duke led to the account's ban. The verified account for Duke, the founder and former Grand Dragon of the Knights of the Ku Klux Klan, was blank Thursday, replaced with a message that the account had been "permanently suspended."

Social media companies have recently been forced to face a reckoning with hate speech on their platforms. Several big companies, including Unilever, Verizon and Starbucks, have announced in recent weeks that they are pausing advertising on Facebook and other social media sites out of concerns social media isn't doing enough to combat hate speech.

The ban follows a similar action by YouTube in June for violating its policy barring videos videos that push extremist views like white supremacy or deny events like the Holocaust or Sandy Hook shooting.

Duke couldn't immediately be reached for comment.