aTHE RAC Foundation has claimed that overpriced motorway service stations could be contributing to tired drivers falling asleep and claims that up to 20% of motorway deaths are caused by drivers' fatigue, writes Lucy Patton.

The foundation was commenting on a report by Auto Express magazine, which visited 20 service stations to check prices on food, fuel, and snacks. The researchers found that on some goods the mark-up was as high as 80%.

Fuel was often 6p a litre more expensive than at nearby garages and the survey also showed that the overpriced meals in service stations were also of poor quality.

The RAC claimed that as well as driver fatigue, a further 20% of motorway fatalities happen on the hard shoulder and that more drivers may run the risk of running out of petrol if they are faced with high fuel costs at service stations.

Mr Edmund King, executive director of the RAC Foundation, said: ''The Auto Express survey may have more frightening implications. One in five of all motorway deaths can be blamed on drivers falling asleep at the wheel.

''It is likely that in some cases the high prices are putting people off stopping. More should be done to encourage motorists to take a break at service areas and more competitive prices would be a step in the right direction.''

He added: ''There is no doubt that many motorists drive extra miles to avoid expensive fuel and run out of petrol. This puts them at risk as one fifth of motorway deaths occur on the hard shoulder. Service areas should provide a better deal for motorists.''