Mr Hammond said that the motorway speed limit could be raised to 80mph to improve productivity, adding that safety couldn't be the sole consideration.

He commented: 'We need to do this on a pretty rigorous cost-benefit basis. At the moment there are a clear set of criteria for making these decisions. Perhaps we ought to ask if we are using the right set of criteria.'

However, in response Coyote, the maker of the Mini Coyote V2 speed camera alert device, said that this sends out completely the wrong signal to drivers.

Andrew Smith, Managing Director of Cobra UK, the UK distributors of the Mini Coyote speed camera alert system, said: 'On the UK's already congested motorways, is it really sensible to suggest that drivers increase their speed in order to get to their destination quicker?

'Road safety has always been, and must remain, the principal driver behind any change in policy – this suggestion appears to signal a worrying change of emphasis.'

He added: 'An extra 10mph on the motorway is not going to make any meaningful change to individual journey times and certainly can't outweigh the potential safety risks, wasteful fuel use and loss of natural resources that are already rapidly running out.

'We welcome the government's relentless drive to tackle the UK's economic difficulties, however using it as justification for this latest idea just doesn't seem credible.'

Coyote also points to the increasing cost to motorists that would result from any such change. With higher speed comes higher fuel consumption – driving at 80mph could use up to 20% more fuel than at 70mph – adding further costs to embattled motorists already struggling with record fuel prices. Add to this the environmental impact from increased CO2 emissions and the benefits of a higher limit seem less clear cut.