Reddit has banned a forum for white nationalists from its social news website, citing the company’s rules against posting personal information and online harassment.

Reddit spokesman Anna Soellner said in a statement that the company banned its “r/altright” forum on Wednesday for repeated violations of its content rules. Soellner said Reddit users can be banned for posting personal information, but her statement doesn’t cite any examples involving the banned forum.

Thousands of users subscribed to the forum named for the “alt-right” fringe movement, a mix of racism, white nationalism and populism. Other sites, including 4chan.org, became popular forums for expressing “alt-right” ideology.

Reddit founder Alexis Ohanian posted an open letter Monday in which he criticized President Donald Trump’s recent executive order restricting immigration from seven countries, calling it “deeply un-American.”