Nearly half of young drivers take to the road in the early morning after a heavy night's drinking, figures out today showed.

Motorists aged 17 to 24 are nearly twice as likely as older drivers to take the controls while still over the legal alcohol limit from the previous evening, a survey from breakdown company Green Flag and road safety charity Brake found.

The two organisations today warned young drivers to ensure they did not drive after a heavy night.

They urged motorists to remember that alcohol can stay in the body for a surprisingly long time, with four pints of strong beer taking about 13 hours to "clear" the system.

Last year, 540 people died and 1,960 were seriously injured in drink-drive crashes - seven deaths and serious injuries a day.

Of the 90,000 convictions for drink-driving in 2006, nearly 20% involved journeys to work or at work.

Jools Townsend, head of education at Brake, said: "It is shocking that nearly half of young drivers will risk their own lives and endanger others by driving the morning after a heavy night's drinking.

"The Government must do more to ensure people are not breaking the law out of ignorance. We need high-profile advertising on this issue and an increase in police powers so they can carry out random breath tests."

Abi Clark, of Green Flag, said: "It's essential that drivers stay fully alert at all times when on the road. At this time of year, it can be easy to get carried away in the festivities.

"We're not saying don't go out and have fun but, to put it simply, if you drink, you shouldn't drive - on the night itself and early the next day."