Social news site Reddit has banned six forums, or “subreddits”, that form the core of its white-supremacist community.

The banned subreddits included “CoonTown”, “WatchNiggersDie”, “bestofcoontown”, “koontown”, “CoonTownMods”, “CoonTownMeta”, although more have been banned since, as users attempt to recreate them and get shut down in turn.

Reddit said the forums exist “solely to annoy other redditors, prevent us from improving Reddit, and generally make Reddit worse for everyone else”.

The company’s new chief executive, Steve Huffman (who posts as spez), announced the bans in a post on the site, alongside the introduction of a new form of sanction for “extremely offensive” subreddits.

“One new concept is ’quarantining’ a community, which entails applying a set of restrictions to a community so its content will only be viewable to those who explicitly opt in. We will quarantine communities whose content would be considered extremely offensive to the average redditor,” Huffman wrote.

“Coontown” and the other white-supremacist subreddits, which their users refer to collectively as the “chimpire”, have long been beneficiaries of the site’s light-touch approach to moderation. Before it was banned, the main group had over 20,000 subscribers, making it one of the largest white-supremacist communities on the internet, after notorious race-hate forum Stormfront.

But, Huffman explained, the subreddits weren’t banned for their content. “We didn’t ban them for being racist,” he wrote. “We banned them because we have to spend a disproportionate amount of time dealing with them. If we want to improve Reddit, we need more people, but CT’s existence and popularity has also made recruiting here more difficult.”

Even as Reddit tightened up its moderation policy over the last few years, Coontown avoided moderation. First the site banned sexualised images of minors, in response to the “jailbait” subreddit; then it banned sexualised photos taken without permission, in response to the “creepshot” subreddit; then “involuntary pornography”, in response to a number of “revenge porn” subreddits and the “fappening” subreddit’s central role in 2014’s iCloud photo hack.

In June, Reddit’s administrators banned five subreddits over harassment concerns. Arguing that “we’re banning behavior, not ideas”, the site removed “fatpeoplehate”, “hamplanethatred”, “transfags”, “neofag”, and “shitniggerssay”. All five subreddits had been directly accused of encouraging harassment and “doxing” – the sharing of personal information – but the bans sparked complaints from users at their seemingly arbitrary nature.

In the process, a campaign against Reddit’s high-profile interim chief executive, Ellen Pao, was started, which eventually led to her departure in July. When Huffman took over as chief executive he confirmed those bans would stay in place.

Another controversial subreddit, “Rapingwomen”, was banned shortly after Huffman became chief executive, but some of reddit’s most notorious subreddits have continued to avoid both closure and quarantine. Groups such as “killingwomen” and “cutefemalecorpses”, which has over 4,000 subscribers, continue to operate as they did before this latest announcement.