The number of motorists driving after drinking excessively the night before is on the increase, a new survey said.

As many as 38% of drivers and motorcyclists said they had taken to the road after a heavy night's drinking, compared with only 28% in a similar poll seven years ago.

The latest survey, from road safety charity Brake and insurance company Direct Line, showed that 45% reckoned they would need to consume two or more units of alcohol for their driving to be affected.

As many as 14% believed it would take three, four or more units to have an effect.

Overall, 35% of the 800 drivers and riders surveyed admitted driving after drinking alcohol (any amount) at some stage during the last year - down from the figure of 51% in 2003.

Brake campaigns director Julie Townsend said: "Drink-driving remains a menace on our roads, devastating people's lives every day. A shocking proportion of drivers seem unaware of the dangers of driving the morning after a heavy night, or even small quantities of alcohol.

"We're appealing to everyone to stay safe over the festive season by planning ahead. Make sure you can get home safely, and stay off the booze if you're driving home or early the next day."

Andy Goldby, director of motor underwriting at Direct Line, said: "Many drivers seem to be oblivious of the risks of driving in the morning after drinking the night before.

"The effect of alcohol on driving ability lasts much longer than a couple of hours after drinking. With this week being the busiest for festive parties, we are urging people not to drink and drive."