MOTORISTS face a new crackdown to tackle the 'growing problem' of people still being over the limit from the previous night's drinking.

The move was announced after the publication of research by the Lancashire Partnership for Road Safety that uncovered an ignorance about how long it takes for alcohol to filter out of your body. Police in the county responded by promising to set up more drink-drive checkpoints in the morning.

They could not provide any figures to prove it was a growing problem, but said officers were definitely perceiving an upward trend. The research found that 80 per cent of people in the county did not know that they would still be over the limit if they stopped drinking at midnight, having consumed 14 units of alcohol and then drove at 7am. That is the equivalent to about five pints of strong lager.

Chief Inspector Val Prince, in charge of road safety, added: "Most drivers caught in the morning are completely unaware that they still have excess alcohol in their system from the night before. Because people often 'feel' sober when they wake up, they assume they are perfectly fit to drive, but this is often not the case."

About 13 per cent of all drink driving offences are committed by people driving the morning after they have been drinking.

Police believe this figure may increase as the new crackdown gets underway.

Linda Sanderson, from the partnership, added: "Many conscientious drivers, who would never dream of drinking and driving while out in the evening, are still waking up and putting themselves and others at risk because they are unaware alcohol is still in their system. Remember, ignorance is no excuse."

Dr Stephen Morton, director of public health for Hyndburn and the Ribble Valley, said it was a tricky topic because the ability to filter alcohol through the system differed from person to person.

But, he added, the rule of thumb was that most people got rid of one unit of alcohol an hour. Dr Morton said: "So it takes two hours for one pint. Anyone drinking between five and 10 pints shouldn't really drive for up to 24 hours.

"Alcohol is an anaesthetic. It makes you feel tired and it will still be affecting you hours later. We would advise people to end binge drinking."