A pro-motorist campaign group has been criticised for misleading comments during the debate over extending 20mph limits in Brighton and Hove.
The national watchdog added that the group, which is made up of businesses and individuals across the city, did not provided any evidence to back up its claims.
It said that widespread 20mph limits would damage the local economy while not improving road safety.
The advert appeared in a local newspaper last year when the council was consulting on whether to extend the restrictions to areas outside the city centre.
The ASA’s verdict was reported on the Latest website.
Speaking after the ASA decision was published today (Wednesday 19 February), Councillor Ian Davey, Brighton and Hove City Council‘s lead member for transport, said: “I welcome this decision.
“We are working hard to address some very difficult issues in the city particularly around road safety.
“20mph speed limit areas are an important part of this work to reduce casualties and make our streets safer for everyone, however they choose to travel.
“I welcome public debate as a vibrant part of democracy but it should be informed by fact.”
The decision was also backed by Brighton and Hove Friends of the Earth (BHFoE), which was one of 15 groups to complain about the advert.
Chris Todd, of BHFoE, said: “It’s just unfortunate that this process has taken so long.
“This advert has already misled the public and influenced the response to a public consultation.
“Getting the ruling now is a little like shutting the stable door after the horse has bolted.”
All 11 complaints were upheld, with the ASA ruling that the advert must not appear again and that the claims made by Unchain the Brighton motorist must not be repeated.
Unchain the Brighton Motorist did not provide a comment by the time of publication.