Twitter suspended numerous accounts associated with the rightwing “western chauvinist” group the Proud Boys on Friday, the eve of the anniversary of the deadly Unite the Right rally in Charlottesville.

Verified accounts belonging to the group and its founder, Gavin McInnes, were suspended for violating the platform’s policy against “violent extremist groups”, a company spokeswoman confirmed. A number of non-verified accounts for various Proud Boys chapters were also suspended.

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The action by Twitter is notable for its timing, coming at the end of a week in which the company bucked a trend set by Apple, Facebook and YouTube to ban the accounts of the conspiracy theorist Alex Jones. Jones built a wide audience on social media while disseminating a toxic mix of conspiracy theories, misinformation and hyper-partisanship, but he was ultimately banned over his hateful speech toward minority groups.

The content moderation policies of all the major internet platforms have come under intense scrutiny by the media and public in recent years, as the companies have lurched from controversy to controversy over issues such as foreign interference in elections, rising political extremism and violence, fake news and misinformation, and targeted harassment campaigns.

In late July, the Guardian asked Twitter why the Proud Boys, which is considered a hate group by the Southern Poverty Law Center (SPLC) and whose members have been involved in numerous violent street battles, were allowed to use the platform. At the time, Twitter declined to comment, but pointed to a policy that read: “Exceptions will be considered for groups that have reformed or are currently engaging in a peaceful resolution process.”

Twitter did not offer an explanation of its change in attitude toward the group on Friday. Many Proud Boys were present at a rightwing rally in Portland, Oregon on 4 August, which saw some scuffles between the rightwing groups and anti-fascist counter-protesters.

Twitter’s decision to designate the Proud Boys as a “violent extremist group” is in part surprising because the group and its leader McInnes have tried to maintain rhetorical distance from the open racism of the “alt-right”, professing to be “western chauvinists” but not white nationalists. The group tends to glorify violence, but claim that it only occurs in self-defense.

News outlets, the Guardian included, have struggled to categorize the group.

The SPLC recently published a report on the way the group uses private Facebook groups to recruit and vet new members. Facebook did not immediately respond to a query from the Guardian asking whether it will follow Twitter’s lead in designating the Proud Boys a violent group.

McInnes did not immediately respond to a request for comment.

A person controlling the Bay Area Proud Boys Facebook page told the Guardian that the group will start using Gab, a social media site that formed as an alternative to Twitter and is popular among the alt-right.

Asked whether the group was concerned that Facebook might follow Twitter’s lead, the person responded: “Were [sic] way ahead of the game and have already been using other means of mediums for recruitment. This will not stop us one bit.”