Switching off street lights to save money could lead to more crashes and more crime, the AA said today.
A number of councils are turning some lights off completely and turning others off at selected times as an economy measure.
The Highways Agency has also switched off some lights on English motorways.
AA president Edmund King said: "There is a fear that in some areas these switch-offs could lead to more crashes and crime.
"Lighting can improve safety for drivers, riders, and pedestrians and deter street crime. The public are in favour of street lighting as a way of improving road safety. Cyclists and pedestrians are more at risk on unlit streets."
Mr King went on: "Local authorities should consider more environmentally-friendly lighting, that can save them £46 a light, rather than putting us all in the dark. In terms of reducing CO2, AA research shows that local authorities will have more effect improving traffic flow than turning off the lights."
An AA study shows that driving outside daylight hours is more dangerous. Only a quarter of all travel by car drivers is between the hours of 7pm and 8am, yet this period accounts for 40% of fatal and serious injuries.
Also worried about the lighting is House of Commons transport committee chairman Louise Ellman.
She told the BBC: "I am extremely concerned that financial pressures are leading to steps which can jeopardise people's lives and increase the number of injuries.
"We've made great progress in recent years in reducing the number of deaths and injuries on our roads. It would be tragic if by switching the lights off, that progress was to be put back many years."
Alistair Scott, president-elect of the Institution of Lighting Engineers, said: "Switching off lights completely is not a good idea. It's a short-term measure and a cause for concern.
"We would rather see lighting levels adjusted to suit the area and the particular time of the day, with some form of lighting maintained at all times."
Buckinghamshire County Council has switched off 1,627 street lights - about 5% of its total - in a three-year pilot scheme.
Kevin Allen, a spokesman for the council, said today: "We have not put road safety at risk and collision rate reductions are, so far, encouraging.
"There was a need to take action as there had been a significant increase in energy costs."
Matthew Lugg, Leicestershire County Council's director of environment and transport, said: "Road safety and personal safety is paramount when we consider whether to switch any street lights off.
"We consult the police and local councils and only proceed if no specific safety concerns have been raised."
He went on: "Experience from other councils which have already switched off lights shows that neither accidents nor crime increase and, in some areas, anti-social behaviour can decrease, as it makes certain areas less attractive to hang around.
"Switching off street lights when and where they are not required can save a considerable amount of carbon emissions and money."Reuse content