A Whitehall advisory body has said that lives could be put at risk if cuts are made to road safety budgets.
The Parliamentary Advisory Councils for Transport Safety (PACTS) said it was important for casualty reduction targets to be put in place and met by 2020.
Robert Gifford, executive director of PACTS, said the number of injuries and deaths on roads across the UK has dropped in the last three years - something that may be of interest to car insurance companies.
And he urged that investment continue in order to reduce the number of casualties even further.
He said: "If we fail to maintain our investment in safety, it will be difficult to keep that trend falling. Without the necessary investment, lives will be put at risk."
His comments came as PACTS released a report for the RAC Foundation called "Tackling the deficit: Where next for road safety?".
The report said some councils had already cut road safety engineering by 60%-80% as well as switching off speed cameras, abolishing or reducing lollipop men and women and cutting road safety education programmes.
The report also said the Government should set a target of reducing, by 2020, the number of people killed or seriously injured on the roads by 50% compared with the average for 2004-08.
Mr Gifford said; "Britain has a long commitment to reducing death and injury on the roads. We need to maintain that commitment even in challenging economic circumstances.
"Road crashes are preventable events. By focusing on cutting these further, we can reduce demand on the health service and enhance the nation's economic capability."
RAC Foundation director Professor Stephen Glaister said: "Britain has made huge strides in cutting road deaths over recent years, but further casualty reduction is not guaranteed. Reduced budgets and more traffic could mean more people killed rather than less.
"To avoid this, the Government must prioritise road safety and send out a clear message to councils that this is an important area of policy."
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