Warning posters are going to be put up in pubs

Police say figures show that more motorists now drink over the limit during the summer than at Christmas.

There has also been a change in the traditional profile of the typical drink-driver, from the middle-aged to 18 to 25-year-olds.

Police warn that barbecues and summer parties can mean drivers drinking "way above the legal limit".

Dyfed-Powys Police will spearhead the summer campaign, being run jointly with the other three Welsh forces - South Wales, Gwent and North Wales.

Posters will go up in pubs showing a police car with the headline "We're going out tonight too - catch you later".

Andy Edwards, acting assistant chief constable of Dyfed-Powys, will launch the campaign in Newtown later, by showing a damaged taxi hit by another car whose driver had been drinking.

Bob Parkes, the Dyfed-Powys road safety officer, said it was not clear why there had been an increase in the percentage of younger drink-drivers.

"For example over 35% of those who were positive or who failed to provide (a sample) involved drivers under the age of 25," said Mr Parkes.

"I think a lot of it is to do with 'I'm fit to drive after one or two'."

But, said Mr Parkes, many drivers did not realise the varying strengths of drinks, such as alcopops or cider.

Hard core

Whereas an average beer might be the equivalent of one unit of alcohol, an alcopop could be considerably stronger.

Police say anyone who deliberately broke the drink-drive laws would be tackled "robustly".

Although officers say it is only a small minority, there was a "hard core that are prepared to flout the law".

Police say their advice is straightforward: If you are going to drive, do not drink.

Experts say that using units of alcohol is an unreliable way of measuring how much it is safe to drink and drive. In addition to varying strengths of drinks, measures poured at home can be much bigger than in pubs.

Police say there is no guaranteed way of knowing how much alcohol is in the body, and advise motorists to have only soft drinks.

But officers also recommend that people going out in groups should nominate a designated driver who will stick to soft drinks.

The summer campaign will run for the next two weeks, and will also include Don't Drink and Drive messages flashed above the two biggest roads in north and south Wales: the A55 and M4.