More than half of motorists are continuing to exceed the 70mph speed limit on motor-ways, with 19 per cent going faster than 80mph, according to Government figures.

A total of 56 per cent of drivers went over the 70mph limit in 2005 - the same percentage as in 2004, the statistics published by the Department for Transport (DfT) showed. The average speed for motorway travel last year was 71mph, a figure that has remained about the same since 1998.

The DfT statistics also showed that nearly half the cars on dual carriageways exceeded the 70mph limit last year, with 13 per cent going faster than 80mph.

On 30mph speed limit built-up roads, 50 per cent of cars went over the limit in 2005 - a drop on the figure of 53 per cent in 2004.

Robert Gifford, executive director of the Parliamentary Advisory Council for Transport Safety, said: "These figures show the continuing decline in the number of motorists breaking the 30mph limit. This is good news for safety and for reducing death and injury on our roads.

"In 1999, 67 per cent of drivers broke the 30mph limit with 31 per cent driving at more than 35mph. By 2005, these figures were respectively 50 per cent and 21 per cent.

"In free-flowing traffic, drivers are increasingly complying with the law. They know that speed kills and that reducing speeds will benefit vulnerable road users -including themselves when they cross the road after parking the car."

He went on: "Similar falls can be seen among motorcyclists. In 1999, 38 per cent of motorcyclists rode at more than 35mph on 30mph roads. In 2005, the comparable figure was 26 per cent.

"We know that the risk of death and injury for a pedestrian doubles between 30mph and 35mph.

"Complying with the urban speed limit saves lives and creates more pleasant communities. The DfT is to be congratulated on maintaining the fall in vehicle speeds. It must keep pursuing policies that are clearly showing results."

A Department for Transport spokesman said: "Over Easter we'll be stepping up our THINK! (road safety) publicity campaigns to make sure that drivers are aware of the dangers of driving tired.

"Our advice to drivers is to take a 15-minute break every two hours. Having a coffee can help, but you need to take a rest too and give the caffeine time to kick in. It's also really important to get a good night's sleep before a long journey. Drivers need to realise that opening the window or switching on the radio won't keep them awake.