Conceding defeat at the election count at Birmingham’s Utilita Arena on Friday, the outgoing Labour leader of the city council, John Cotton, made a plea. “What I would encourage the next administration in this city to do, whatever form that administration takes, is that it ensures it champions the diversity of this city,” he said.

Labour’s 14-year rule of the local authority had come to a crashing end, with Reform emerging as the largest party with 22 councillors so far, followed by the Greens on 19, albeit both parties a long way off the 51 needed for a majority.

Labour lost more than 1,400 councillors across the local elections in England on Thursday and lost power in Wales for the first time. Nigel Farage described the election results, in which Labour also lost ground in Scotland, as a “truly historic shift in British politics”.

Reform UK’s success has caused trepidation among many members of minority communities across the UK, with concerns there could now be a rise in hostile rhetoric.

Mus, a member of Brummies United Against Racism, a group of neighbours in Birmingham who came together after a far-right group distributed leaflets to their doors, described the success of Reform as “really concerning”.

“We are really disappointed. We’ve been campaigning to make sure our city is a safe space for our communities,” she said. “We know if we get a Reform government what that means to our communities – black, brown, migrant communities.”

Shaista Gohir, the chair of the Muslim Women’s Network, based in Birmingham, said people were feeling worried and anxious. “What does that mean for [communities] in terms of our safety, the quality of services that we’re going to receive,” she said. “Is anti-Muslim rhetoric going to really escalate locally? There is a lot of concern.”

Similar concerns can be found in other parts of the UK. In Sunderland, a newly elected Reform councillor was suspended days after the election after the anti-racism group Hope Not Hate uncovered a now-deleted post in which he said: “Carnt [sic] believe amount of nigerians in town … should melt them all down and fill in the pot holes.”

Shaista Aziz, an anti-racism campaigner and community organiser based in Oxford, said minority communities were bracing themselves for a surge in racism, with friends and family expressing fears about being able to live safely in the UK.

“Many British Muslim communities feel scared and intimidated by the Reform victories and also feel sad that their neighbours have voted for a party that openly calls for the deportation of members of our communities and can’t call out their councillors for their deeply racist rhetoric,” she said.

Talat Yaqoob, an equalities campaigner based in Edinburgh, said people were worried about their safety and their future after Reform won 17 seats in the Scottish parliament, taking joint second place with Labour behind the SNP.

“We know marginalised communities are worried about Reform’s wins and how these wins are interpreted on the ground by those who are already targeting them,” Yaqoob said. “They are worried for their safety, they are worried about their futures. Now that we have some Reform MSPs, they need to be held to account, they must be held to the standards we expect of those with the privilege of public office – that means calling out their disinformation and their divisive language.”

Pinar Aksu, a campaigner for Refugees for Justice, based in Glasgow, said: “We’ve now entered a new era of politics where racism is in our parliament.” She attended a unity march in Glasgow city centre on Saturday with hundreds of other anti-racism activists. “It was good to come together to shared these feelings of disappointment and anger,” she said.

For Gohir, the concerns extend to some independent campaigners in Birmingham. Akhmed Yakoob, a criminal lawyer with a large social media following, formed an electoral pact with George Galloway’s Workers party to field about 70 prospective councillors across the city. During the campaign trail, he attracted controversy after he was heard saying in Sky News footage: “Zionists control everything”. Yaqoob also described a video of Zack Polanski, the Green party leader, dancing at event in Trafalgar Square as “degeneracy”. Yakoob has denied allegations of antisemitism.

A Labour councillor in Birmingham, David Barker, said it had been the worst campaign he had fought in and that “homophobia, transphobia are more acceptable now”. “It really doesn’t represent, I think, the way most people in Birmingham feel,” he said. “But unfortunately, in a deeply divided election when you can win with 20% of the vote, you are going to get sometimes a minority view winning.”

At the election count on Friday, the Guardian asked the Reform MP Richard Tice for a response to the concerns some communities in Birmingham may feel about the rise of Reform.

Tice interrupted several times and said: “If they were fearful, why would they be voting for us?” He added: “I’m concerned for the Jewish community and about the antisemitism, the abuse they get, and I want people at the Guardian and other lefty newspapers to focus on that rather than one other particular community. Are we clear?”

For Mus, the work of her campaign group will only accelerate in the face of Reform’s gains. “We worry about the implication for residents in our city, but in our responses now we have to work harder, we have to double our efforts because our futures depend on it,” she said. “We’re not going to allow them to divide us.”

Reform UK and Akhmed Yakoob have been approached for comment.