Plans to introduce 'safer' 15mph zones on major city roads would be worse for the environment than higher speeds, motoring campaigners warned.

The City of London Corporation this week unveiled draft proposals to reduce speed limits in the Square Mile as part of its first ever long-term strategy to improve road safety and cut pollution.

Officials said while 20mph zones had helped to curtail the number of deaths and serious injuries to cyclists in the City, record levels of workers meant the overall number of fatalities had not decreased.

The corporation, which governs the City of London, suggested a city-wide 15mph restriction could help "eliminate" deaths on the streets by encouraging motorists to show safer behaviours behind the wheel.

The Department for Transport would have to approve any 15mph restriction, thought to be the first of its kind on city centre roads, which the corporation said it wants to adopt by 2022.

But motoring groups IAM RoadSmart and The AA claimed the the move would not help save lives and could even worsen pollution levels with the constant stop-start of engines causing more harmful emissions to be released.

IAM RoadSmart spokesman Rodney Kumar, said: "IAM RoadSmart is against blanket reductions to 20mph as is the case in many town centres, and we don’t see a proposed reduction to 15mph having the desired effect in terms of congestion, pollution or road safety.