A study in the British Medical Journal has said that any economic benefits of raising motorway speed limits are outweighed by the increased risk of crashes.
A report from the London School of Hygiene and Medicene has said that proposals to raise the speed limit on motorways from 70 to 80 mph would lead to more fatal crashes.
The report's authors drew attention to statistics showing that after speed limits were raised in America in 1995 there was a 16.6% increase in the number of deaths caused by car crashes.
They said: "It is difficult to see how any benefits of an 80mph speed limit would outweigh the costs.
"Past evidence shows that speed limit increases lead to substantial rises in road deaths, as well as other potential negative health and economic impacts."
The report challenged the government to produce evidence in support of the change, particularly in light of the multiple car crash on the M5 this November in which seven people died.
Copyright Press Association 2012