Grenfell fire survivors have condemned as “callous and sickening” bonfire party-goers who burned a model of the tower with brown faces at the windows.
Video footage shows a group of white people lifting it onto a ready-made bonfire, and laughing as it goes up in flames.
The film, apparently shot for bonfire night in a back garden where there is a George cross flag in the background, shows cut-outs of faces at the windows. Brown paper had been used for most of them.
Mocking cries of “help me” and “stay in your flat” are heard as the flames take hold.
Other onlookers say: “Jump out the window” and “All the little ninjas getting it”.
One person is heard mentioning “really bad taste” but the group continues to laugh and joke while the fire rages.
A cheer goes up as the fully burning cardboard model finally collapses to the ground.
Campaign group Justice 4 Grenfell said the footage had caused "great alarm and distress".
"We are disgusted and shocked at the inhumanity and callousness of those involved in this video," the group said in a statement.
"This was an unnecessary sickening act of hate against those who, through no fault of their own, have experienced the worst since 14 June 2017.
"This is clearly a hate crime, and as a society we should never tolerate these types of blatant acts of hatred."
The video was initially widely shared on WhatsApp, then later other platforms, where users overwhelmingly condemned the scenes.
Justice 4 Grenfell highlighted that there have been calls recently for social-media platforms to block and instantly remove hateful content.
"We have an expectation that the police will look into this robustly and that the perpetrators will face the full force of the law."
London Fire Commissioner Dany Cotton said: “This is an appalling and disturbing video.
“To intentionally use and mock the Grenfell Tower fire in this way will cause deep pain and offence to the bereaved, survivors, the local community and all of the emergency services who will never forget that night. It cannot be justified on any level.”
Campaigners reported the group’s actions to police, saying it was incitement to racial violence.
Some people took photos before the model was manoeuvred into place.
Home Secretary Sajid Javid condemned the "disgusting, shameful" behaviour. "These people are a disgrace," he wrote on Twitter.
Denise Richards, a community development worker from Derby, who was among many people reporting the event to police, said: “When I received this video and watched it, I thought it was unreal. I felt sick. I was shocked.
“Someone has planned this – gone to the trouble of getting the cardboard and brown paper and designing it.
“They must be sick. It’s premeditated racism.
“The pain from the Grenfell tragedy will never ever leave those affected. Even people living nearby who witnessed the fire are still struggling.
“I’m so angry. There will be a demonstration if the police don’t take this seriously.”
It is not known where the event happened, but some people viewing the video said the accents suggested Essex or London.
At least 72 people were killed in the inferno that engulfed Grenfell Tower in west London on 14 June last year. It was the worst residential fire in the UK since the Second World War.