DRIVERS are being warned that just one drink has the potential to put them behind bars this Christmas - even if they are below the legal alcohol limit.

Superintendent Martin Deacon, head of road policing for North Yorkshire Police, said officers would arrest motorists who were not driving to an acceptable standard and charge them with being unfit to drive.

Those who are found to have even the smallest amount of alcohol within their system face similar penalties to convicted drink-drivers - a compulsory 12-month driving ban, a licence endorsement of three to 11 points, a fine of up to £5,000 and a potential six months in prison.

Supt Deacon said the safest option for the county's motorists was to adopt a zero tolerance approach because officers would be carrying out breath tests on all drivers involved in any accident.

Officers have already begun their Christmas clampdown, with checks taking place on North Yorkshire's roads every day until January 2, often at multiple locations.

Last Christmas, 85 drivers failed breath tests and drink-driving convictions continue to rise, despite police warnings, with 252 drivers convicted in North Yorkshire last year, compared to 212 in 2002.

Officers will be targeting "morning-after" drivers in particular who are often unaware that they are breaking the law.

Statistics suggest that 15 million motorists underestimate sobering-up times resulting in one in three driving the morning after, while over the limit. The drink-drive limit stands at 80mg of alcohol in 100ml of blood and 35 micrograms of alcohol in 100 millilitres of breath.

But that figure cannot be translated accurately into units because body size, age, gender and metabolism can alter how quickly alcohol is absorbed into the blood.

It can also be difficult to keep track of what you have had to drink. Last month, the Evening Press reported that 40 per cent of York pubs had taken to serving "super-sized" measures of spirits, substituting the traditional 25ml for 35ml as standard, and selling wine in 175ml or 250ml glasses.

Drink-driver Benjamin Kaye, 23, of Toulson, near Tadcaster, began a three-and-a-half year jail sentence last month after admitting crashing his company car at 70mph during a police chase on the A162, killing front seat passenger Mark Beal, 21, of Lumley, near South Milford.

Kaye was also banned from driving for six years by the Honorary Recorder of York, Judge Paul Hoffman, who heard he had been slightly over the drink-drive limit.

In September, racehorse owner Michael Hall was jailed for three-and-a-half years for killing 32-year-old Sarah Lunn, personal assistant to Thirsk trainer David Nicholls, in a high-speed crash at Easingwold.

He was one-and-a-half times over the drink drive limit.

Updated: 10:44 Saturday, December 11, 2004