Government plans to increase the speed limits on motorways to pep up the economy have come under attack from safety experts.

70mph has been the speed limit on motorways since 1965, but the Department of Transport has suggested that increasing the speed limit to 80mph could well be beneficial for the economy, making journeys shorter and getting deliveries and commuters to their destinations quicker.

The Department of Transport's report predicts "…economic benefits, worth hundreds of millions of pounds per year, particularly from savings of travel time". Transport secretary Phillip Hammond has backed the proposal.

Studies show that 49% of drivers already break the 70mph speed limit. Hammond told The Times "If 50 percent of the population are routinely breaking the law it's actually the law that needs looking at,"

However, not everyone is happy with speeding up Britain. RAC founder Professor Stephen Glaister predicted not only an increase in deaths on the road but environmental impacts too.

"There are good reasons for making 80 the new 70, and good reasons not to. Drivers travelling that 10mph quicker might reach their destination sooner, but will use about 20% more fuel and emit 20% more CO2." said Glasier.

Director of RoadPeace Amy Aeron-Thomas, the national charity for road crash victims in the UK, wrote in the Daily Mirror "It seems the only possible reason for the increase is that the Government thinks time-saving justifies the increased risk in casualties as well as the increase in both carbon emissions and fuel consumption."

Greenpeace's Emma Gibson told The Guardian "At a time when North Sea oil production is going down and we are ever more reliant upon unstable regimes and fragile environments to fuel our cars, the transport secretary's decision will raise oil consumption and carbon emissions when we need to cut both."

The change to 80mph is proposed to be introduced to UK roads in 2013.

Main image: Speed limits introduced in 1965 – Getty images