Since early this week, state officials have been attempting to debunk misinformation on social media that has blamed both left-wing and right-wing groups for the fires that have killed at least six people in Oregon this week.

Facebook, which earlier was attaching warning labels to such posts, decided to move to the stricter approach after “confirmation from law enforcement that these rumours are forcing local fire and police agencies to divert resources from fighting the fires and protecting the public”, the spokesman, Andy Stone, said in a statement on Twitter.

Stone called the decision “consistent with (Facebook’s) past efforts to remove content that could lead to imminent harm given the possible risk to human life as the fires rage on”.

Flames have destroyed thousands of homes in days, making Oregon the latest epicentre in a larger summer outbreak of fires sweeping the western US.

One of Facebook’s third-party fact-checking partners, PolitiFact, wrote on Thursday on its website that dozens of posts blaming Antifa – a largely unstructured, far-left movement – for the wildfires had been flagged by Facebook’s systems, and that collectively the posts had been shared thousands of times.

The FBI on Friday said in a statement that after investigating several reports that extremists were responsible for setting wildfires in Oregon, it found them to be untrue.

Earlier this week, police in Medford, Oregon, debunked a false post using the police department’s logo and name suggesting that five members of the Proud Boys, a men-only, far-right group, had been arrested for arson.