Rishi Sunak is preparing to curb English councils from introducing new 20mph speed limits, according to reports.

The Prime Minister will unveil the measure as part of a Plan for Motorists at the Tory conference in Manchester, according to several newspapers.

He is reportedly planning to limit the power of local authorities to impose new 20mph zones, restrict the number of hours a day cars are banned from bus lanes, and scale back low-traffic neighbourhoods (LTNs).

The Guardian reported that the plan also involves reducing the ability of local authorities to impose fines from traffic infractions such as the misuse of yellow box junctions.

In July, Mr Sunak pledged to crack down on “anti-motorist” policies.

This came after the Uxbridge and South Ruislip by-election, where the Tories held the seat in a campaign dominated by the row over London’s ultra low emission zone (Ulez) expansion.

Earlier this month the Prime Minister delayed the ban on the sale of new conventionally fuelled cars and vans from 2030 to 2035.

A Department for Transport (DfT) source described the reports of new measures aimed at helping drivers as “speculation”.

Downing Street was approached for a comment.

Earlier this month, Wales became the first country in the UK to drop the default speed limit from 30mph to 20mph for restricted roads.

Treasury minister Andrew Griffith said the Prime Minister is “very focused on making sure that motorists get a fair deal”.

He told Sky News: “A blanket measure is rarely a good idea. So if that’s something like we’ve seen in Wales, where vast parts of that province have had arbitrary speed limits imposed on them, then I don’t think that’s the right approach, just as it’s not the right approach to blanket the whole of Greater London with Ulez and a higher cost for motorists.”

He added on LBC: “I think we are the party of the motorist and that’s not just something that has happened now.”

Nicholas Lyes, director of policy at the road safety charity IAM RoadSmart, said 20mph zones “have a role to play” but the “proliferation of blanket limits without physical changes to road layouts means compliance is often poor”.

Local authorities are “usually best placed” to decide the location of the zones but there “is an argument” to strengthen guidance on how that happens, he added.

RAC head of policy Simon Williams said: “While we support the use of 20mph limits being used where they are needed most, such as outside schools, on residential streets and in urban areas where there are lots of pedestrians, implementing them in widespread fashion may unnecessarily lengthen journey times by slowing down traffic, and possibly even increase congestion.

“We need councils to strike the right balance between making our roads safer and ensuring the smooth flow of traffic, in all its forms.

“We need to see the detail of the PM’s plan to see whether what’s proposed will really help with that.”

An RAC-commissioned survey of 3,102 motorists indicated that the most common reason drivers give for exceeding 20mph limits is because they think the restriction is inappropriate for thatparticular road.

The poll was conducted by research company Online95 between April and May last year.

Six leading cycling and walking organisations criticised the reported Plan for Motorists.

A joint statement by the chief executives of Bikeability Trust, British Cycling, Cycling UK, Living Streets, Ramblers and Sustrans said: “When ministers could be promoting public transport, cycling and walking as cheap sustainable options in a cost-of-living and climate crisis, they’re entrenching congestion and reliance on driving for short local journeys.

“When the Government could respect people’s freedom to choose how they travel, it’s removing the alternatives.

“This is a plan that looks no further than one way of travelling and will make the roads worse for those occasions when people do need to drive.”

The Welsh Government is predicting its change to 20mph speed limits will save up to 100 lives and 20,000 casualties in the first decade.

First Minister Mark Drakeford said there is “incontrovertible” evidence that “driving more slowly in built-up urban areas saves people’s lives”.

A DfT-commissioned study published in November 2018 found 20mph limits in residential areas were supported by the majority of residents and drivers.

The research said cutting limits from 30mph to 20mph resulted in a reduction in average speed of less than 1mph, but vehicles travelling faster before the change generally lowered their speed more than slower vehicles.

The report concluded there was no evidence of a significant drop in the number of crashes and casualties after the introduction of 20mph limits.