The maker of Fortnite has pulled adverts from YouTube amid concerns that promotions for the video game, which is popular with children, were appearing alongside comments posted by paedophiles.

Epic Games confirmed it had withdrawn its adverts from the Google-owned site, joining Nestlé in temporarily abandoning it due to the latest scandal over inappropriate content.

A YouTube user called Matt Watson had posted a video highlighting a “wormhole into a softcore paedophile ring” on the site. He showed how in a matter of clicks with a new YouTube account, users could find videos filled with provocative comments about children.

“Paedophiles are trading social media contacts; they’re trading links to actual child porn in YouTube comments; they’re trading unlisted videos in secret, and YouTube’s algorithm through some glitch in its programming is facilitating their ability to do this,” he said in the video.

The scandal poses a challenge for YouTube because the videos themselves are not necessarily problematic. They are mostly innocent videos of young girls playing, doing exercises in their family home, or taking part in gymnastics. The issue is in the comments section, where YouTube users have left sexually provocative messages and shared tips on when to pause the videos to take compromising still images of the children.

After watching a few such videos on a new YouTube account, Watson described how the site’s algorithm – designed to provide users with content they might like, to keep them watching – would serve up endless videos of apparently underage children where the comments section contained inappropriate comments.

Many of these videos were also accompanied by adverts placed by major brands such as Nestlé, Fortnite and Disney.

In a sign of the complicated media ecosystem that now exists on YouTube, where individual video creators can earn a share of the site’s advertising revenue, the reaction to the story from the wider YouTube community has not been entirely positive.

Many other prominent YouTubers have accused Watson of overreacting. Some have criticised him for going public with his claims that paedophiles were using the site’s comments section. These YouTubers accuse Watson of trying to drive away advertisers from the site, depriving them of their often substantial incomes and attempting to cause an “adpocalypse”.

This is a reference to previous occasions when large advertisers pulled money from the site over concerns about YouTube’s ability to ensure their adverts did not appear alongside disturbing or inappropriate content, such as videos published by terrorist organisations or hate preachers.

A YouTube spokesman said of the latest claims: “Any content – including comments – that endangers minors is abhorrent and we have clear policies prohibiting this on YouTube.

“We took immediate action by deleting accounts and channels, reporting illegal activity to authorities and disabling comments on tens of millions of videos that include minors. There’s more to be done, and we continue to work to improve and catch abuse more quickly.”