It is hoped variable limits would ease congestion

The changes, aimed at easing congestion, would affect parts of motorways which have variable speed signs, such as the M25 around London.

But road safety groups have expressed opposition to the plan.

RoadPeace, a motoring charity, argues that "any raising of the limit would make the roads more dangerous".

The suggestions are now being passed on to the Highways Agency which is responsible for motorways and major trunk roads in England.

AA Motoring Trust director Bert Morris has expressed support for variable motorway speed limits.

The proposal to raise the limit on motorways is irresponsible and flies in the face of road safety advice Mary Williams OBE Brake

He said: "The current 70mph limit on motorways works well and should not be altered.

"However, on motorways where there are variable speed signs a limit of 80mph should be introduced when traffic flow and road conditions permit."

He added: "If technology exists to reduce speeds on motorways at certain times, then it ought to be possible to raise speeds when it is suitable to do so."

But Mr Morris also added a note of caution, saying there was a need to ensure that drivers did not break the 80mph limit if it were introduced.

However, the suggestions have been criticised amid safety concerns.

Mary Williams OBE, the chief executive of road safety charity Brake, said: "The proposal to raise the limit on motorways is irresponsible and flies in the face of road safety advice and convincing evidence from the USA and elsewhere that raising limits increases casualties.

Safety fears

"We should be prioritising better enforcement to make our motorways safe, not making them more dangerous."

But Paul Watters, the AA Motoring Trust's head of road policy, dismissed fears that the proposal would make roads more hazardous.

"The changes described would improve safety," he said.

Mr Watters said many accidents stem from the different speeds adopted by drivers, which can vary "between 70mph and 90mph".