YouTube will stop recommending videos promoting conspiracy theories such as those contending the 9/11 attacks never took place. (Photo: Pixabay)

YouTube said Friday it will stop recommending specious videos such as those claiming the earth is flat or promoting bogus theories about the September 11, 2001 attacks. The global video streaming service planned to modify its viewing recommendation system gradually, starting in the United States and later expanding to other countries.

Google-owned YouTube, part of the Alphabet holding, said it is scrutinising how to reduce the spread of content that comes close to but doesn't quite cross the line of violating its community guidelines. "To that end, we'll begin reducing recommendations of borderline content and content that could misinform users in harmful ways. Such as videos promoting a phony miracle cure for a serious illness, claiming the earth is flat, or making blatantly false claims about historic events like 9/11," YouTube said in a blog post.

YouTube estimated the change would affect less than one percent of content at the service but would improve the experience for users. Videos deemed to be just shy of violating community guidelines will remain accessible and come up in search results, they just won't be suggested as worth watching, according to YouTube.

"We think this change strikes a balance between maintaining a platform for free speech and living up to our responsibility to users," YouTube said. Both human review and machine learning will be used to train the recommendation system on questionable videos, the company said.