The BFI London Film Festival (LFF) has cancelled a screening of a documentary about the far-right over “safety” concerns.

Undercover: Exposing The Far Right, which uses hidden cameras to cover far-right figures across the UK and Europe, was to be part of the 68th festival over the weekend, but has been withdrawn.

Kristy Matheson, director of BFI London Film Festival, said: “After exploring all the viable options to screen this film at a public film festival we took the heartbreaking decision to not present Undercover: Exposing The Far Right at the LFF.

“I think the film is exceptional and easily one of the best documentaries I have seen this year.

“However, festival workers have the right to feel safe and that their mental health and wellbeing is respected in their workplace.

“I took on board the expert opinion of colleagues around the safety and wellbeing risks that the screening could have created for audiences and the team and that informed our decision, which we did not take lightly. The film is incredibly important and we wish it the very best.

“The BFI is a proud supporter of the film as a financier through the BFI doc society fund, awarding National Lottery funding.”

The movie, directed by Smash & Grab – The Story Of The Pink Panthers director Havana Marking, follows campaigners from Hope not Hate, which describes itself as an organisation working to expose and oppose far-right extremism.

Ms Marking called it “a very powerful film”, for which she and her team had spent “two years following the brave and inspiring work done by Hope not Hate in an extraordinarily febrile time”.

“It is shocking to see the extent of far-right influence in both street level and elite ‘intellectual’ circles,” she added.

“I understand the fear that people have, but am very disappointed that no alternative method of screening at LFF could be found.

“It is getting harder and harder to make these films and to lose this audience was upsetting.”

An online description says it is about exploring far-right activists as the UK “reels from the impact of this summer’s riots”, and the money behind the way “prejudice” is disseminated online.

Nick Lowles, chief executive of Hope not Hate, who appears in the documentary, said: “Safety must always be an utmost priority. But we can’t deny that it is disappointing to see the brave work of our staff being denied the widest possible audience.

“Now, more than ever, the true nature of the far right, in Britain and abroad, needs to be exposed.”

Channel 4 will broadcast the documentary on Monday at 10pm.

The broadcaster has been contacted.