(Bloomberg) -- UK Transport Secretary Mark Harper attacked local government efforts to rein in road congestion, tapping in to fringe conspiracy theories around so-called 15-minute cities. 

Describing the governing Conservative Party as “proudly pro-car,” Harper attacked the Labour Party for making driving more expensive, singling out London Mayor Sadiq Khan for expanding anti-pollution charges on cars and “blanket” 20 mile-per-hour speed limits in Wales.

Referring to 15-minute cities, a concept whereby workplaces, schools and amenities are ideally located within a short walk or bike ride from home, Harper appeared to repeat a key tenet of conspiracy theorists, particularly on the climate skeptic fringe, who see them as a tool of government control. 

“What is sinister, and what we shouldn’t tolerate, is the idea that local councils can decide how often you go to the shops, and that they can ration who uses the roads and when, and that they police it all with CCTV,” he said.

Harper’s remarks show how Prime Minister Rishi Sunak’s governing Conservatives are tapping into populist undercurrents as they seek to close a 20-point polling gap on the opposition Labour Party, with a general election widely expected next year. The Tories are also rowing back on measures to eliminate carbon emissions, and engaging in an internal debate on whether the UK should leave the European Convention on Human Rights.

Read More: A 15-Minute City Freakout Is a Case Study in Conspiracy Paranoia

Conspiracy theories about 15-minute cities are prominent on social media and have triggered protests in Oxford, Bath and other places. 

“I am calling time on the misuse of so-called 15-minute cities,” Harper said. “The government will investigate what options we have in our toolbox to restrict over-zealous use of traffic management measures including cutting off councils from the DVLA database if they don’t follow the rules,” he said, referring to the national repository of car license plates and owners.

Harper said a review into the use of so-called low-traffic neighborhoods is ongoing, and that the government will change guidance to local councils to state that 30 mph should be the default speed limit, with lower limits used only “where there’s good reason.”

Read More: Sunak Says Filling UK Potholes as Pressing as Pricey HS2 Project

One thing the minister didn’t mention was the transport topic that dominated the run-up to the Tory conference: whether the government will scrap or delay the Birmingham to Manchester leg of the HS2 high-speed rail project because of spiraling costs. 

(Adds details on 15-minute cities in third paragraph.)

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