MOTORISTS who drink and drive over the festive season are facing the toughest police ­crackdown to date, with more officers than ever before on patrol to catch out those who get behind the wheel while they are over the limit.

The annual drink-driving campaign was launched in Edinburgh yesterday, with warnings that consuming even one alcoholic drink before driving makes motorists three times more likely to die in a car crash.

It will run for the next four weeks, with all of Police Scotland's 17,000 officers deployed at various times on patrols in key locations to catch offenders.

Police will use a combination of marked and unmarked cars, with resources targeted at known blackspots.

The ramped-up campaign against drink driving continues the hardline stance taken on road policing since the single force took over in April, which has led to a fourfold rise in the number of drivers stopped for speeding in Edinburgh.

It will hammer home to ­motorists the potential legal and personal consequences of a conviction.

Superintendent Iain Murray, head of road policing, said: "Every year we raise the issue of drink-driving and every year there are still people who break the law with no consideration for others.

"Drink or drive, it's your choice, but you can't do both. In Scotland there are over 17,000 police officers and there has never been a greater priority and focus on casualty reduction and making Scotland's roads safer.

"If you think you are OK as you've only had 'one' or a couple of small drinks then think again, it doesn't matter whether you're just over the limit or well over the limit - you're a drunk driver."

Drink-driving kills about 30 people a year in Scotland. The festive campaign - which urges motorists to avoid drinking at all before driving - comes amid delays in cutting the drink-drive limit north of the Border from 80mg/100ml of blood to 50mg.

The new lower limit, announced in March, would bring Scotland into line with most of Europe and is expected to save about 17 lives a year. It would also mean drivers would be over the legal limit after consuming just one glass of wine or a pint of beer.

However, it is understood the process of bringing in the new limit has been hampered by ­Westminster prioritising the development of new "drugalysers" for use in England and Wales. While the Scottish Government can set legal limits for Scotland, the process of recalibrating breath-test equipment is reserved.

Justice Secretary Kenny MacAskill said he was disappointed about the delay to putting the new limit in place.

He added: "We know it would save lives on Scotland's roads, but it's a relatively complicated process and we are relying on our colleagues at Westminster to carry out the recalibration."