Conservative party staff and activists are secretly operating a network of Facebook groups that have become a hotbed of racism, misinformation and support for criminal damage. An investigation has identified 36 groups that appear to be separate grassroots movements opposing the expansion of ultra-low emission zone (Ulez) schemes to reduce air pollution. They do not say they were set up by the Conservatives as part of a coordinated political campaign. The closed groups – which have a combined membership of 38,000 – have been a forum for Islamophobic attacks on Labour’s London mayor Sadiq Khan, with members calling him a “terrorist sympathiser” and a “khaki punt” and saying they would pay to get him “popped”. Other posts promote white supremacist slogans, antisemitic conspiracy theories and have encouraged the destruction of Ulez enforcement cameras. The findings by Greenpeace’s investigative unit, Unearthed, shared with the Observer, are the latest controversy to embroil the party over its campaigning tactics and attacks on Khan. Its former deputy chairman, Lee Anderson, was suspended in February after claiming “Islamists” were controlling the London mayor, and a Tory attack video used scenes of a panicked crowd at a New York subway station to claim Londoners were in fear of crime. Senior Tories have made posts in some of the groups, including the London mayoral candidate Susan Hall, who is a member of six groups and has posted in two. Hall did not respond to requests for comment. The findings also raise questions about transparency. It is not made clear to the groups’ members that they are linked to the Conservatives. But most share the same three administrators, believed to be two CCHQ staffers and an activist who helped run an MP’s digital campaigns. Rachel Cromie, an administrator of all 36 groups, is a Tory councillor in Haywards Heath, Sussex. Her current register of interests lists Conservative campaign HQ in a section on employment and she has previously been described as an area campaign manager for the party. An earlier register of interests shows she was head of operations for a political consultancy founded by a former consultant at Cambridge Analytica. Cromie did not respond to requests for comment. Another Conservative party employee, who has been one of its digital campaign managers since February this year, is an administrator of 27 groups. Others include councillors, party officials and a local mayor. The Observer also found Tory activists posting in the groups without declaring their political affiliation. One posted a meme calling Khan an “arse” alongside laughing emojis. The approach appears to have enabled the targeting of political messages at certain groups without the need to follow Facebook transparency rules, which require formal ads to carry a disclaimer. The Conservative party said it would review its “processes and policies” regarding Facebook groups in light of the findings. It did not say whether the running of the groups had been funded centrally or comment on the failure to make clear they were linked to the Tories. A spokesperson distanced CCHQ from the racist and abusive comments, saying the party “unequivocally condemns all discriminatory language, and never encourages nor condones vandalism or criminal activity”. Seven Conservative MPs, including Sir Bob Neill and Steve Tuckwell, who held Boris Johnson’s Uxbridge and South Ruislip constituency for the Tories in last summer’s byelection, are also members of groups in the network. Neill, Conservative MP for Bromley and Chislehurst, said he did not believe the posts represented the majority of people opposed to Ulez, but that they were “completely inappropriate” and he did not tolerate or condone them. Chris Philp, policing minister, was previously found to be a member of one of the groups and said this weekend that he condemned unacceptable abuse and endorsement of criminal damage. Tuckwell did not respond to requests for comment. There is no suggestion the racist posts or those encouraging vandalism were made, or engaged with, by Conservative politicians or staff. The groups – which have names like “Hillingdon say no to Ulez expansion” and are described as a “digital community for residents” – were mostly set up in early 2023 before the Uxbridge byelection, but are now being used to promote Hall’s campaign and attack Khan. There is a group for almost every London borough, as well as for commuter-belt counties including Kent, Essex and Surrey. Researchers from Unearthed joined six of the bigger groups and found dozens of racist posts and virulent abuse of Khan, including users saying they would like to see him killed. Conspiracy theories – including that the World Economic Forum is using green measures to restrict individuals’ movements and that Ulez cameras are equipped with facial recognition technology – are widespread. Posts encouraging vandalism have also been allowed to circulate. In the Kent Facebook group, an anonymous participant posted a call to action in February saying “blade runners” were “needed urgently” to target Ulez cameras. The post included a picture of a man holding a flaming molotov cocktail, his face painted with the St George flag, emblazoned with the words: “Fcuk Ulez. People must now stand together. If Khan gets in the PURGE must begin with NO REGRETS.” The groups’ rules state that they ban hate speech, bullying, “degrading comments” and posts that are about “illegal activity or encourage others to break the law”. Such posts are supposedly deleted and the member permanently banned. But the content appears to have been allowed to spread without intervention from the Tory figures who oversee the groups and have the power to police their contents. Ami McCarthy, political campaigner at Greenpeace UK, said: “These groups are an absolute cesspit of vile racism and hate speech, as well as a breeding ground for dangerous conspiracy theories. That they’re being managed by Conservative operatives speaks volumes about the direction in which the party has gone, and just how toxic these anti-Ulez campaigns have become. The party should launch a full investigation into this whole shameful scandal and everyone involved.” Georgie Laming, director of campaigns and communications at the anti-extremism group Hope Not Hate, said the groups went “so much further” than criticising Ulez policy and that the groups were “whipping up hate and spreading misinformation for short-term political gain”. A Labour source said the party was considering reporting some of the content to the police. Targeting tactics have previously been used to spread polarising messages, most famously during the Cambridge Analytica scandal in which pro-Brexit campaign messaging was aimed at some voters and hidden from others. Last month, the Observer revealed that divisive ads were being pushed to working-class over-50s by the Tories. The ads had been aimed at cleaners, builders, and people interested in reality TV, Primark and football – but hidden from those interested in “environmental issues” and social change. With highly engaged audiences, private Facebook groups provide an even more effective way to push targeted political messaging without the same scrutiny received by traditional ad campaigns. Meta, which owns Facebook, was contacted for comment.