Scotland's largest police force will today begin using youngsters to catch licensed traders selling alcohol to under-18s.

Strathclyde Police's test-purchasing scheme will use "intelligence-led" stings rather than the more random approach adopted during the Fife pilot with 16-year-olds attempting to buy liquor in pubs, off-sales and supermarkets.

The roll-out comes as police chiefs across Scotland launch a crack down on alcohol-fuelled violence, warning those caught behaving in such a way would be dealt with severely.

The three-week campaign is taking place in the run-up to Christmas and is backed with £1m of Scottish Government funding.

As well as tackling drink-related disorder, police will be trying to curb the amount of alcohol bought by under-age drinkers by targeting adults buying liquor for under-18s.

Police will be targeting street drinking as part of the drive, the latest phase of the Safer Scotland anti-violence initiative, whose co-ordinator, Chief Inspector Andy McKay, said: "Christmas is a time when pubs and bars are at their busiest and many of those attending festive parties will be inexperienced drinkers who are more susceptible to becoming either victims or perpetrators of alcohol-fuelled violence.

"Make no mistake, anyone caught can expect to be dealt with severely. We want to send out a clear message that such behaviour is unacceptable."

He added: "This isn't just about clamping down on those who engage in alcohol-related violence. We need to educate people about the dangers of excessive drinking and the effects it can have."

Justice secretary Kenny MacAskill announced in September that £1m was being made available to help reduce alcohol-fuelled violence on Scotland's streets over the festive period.

As well as being used to crack down on violence, the money will fund initiatives such as late-night taxi marshal schemes and more high-profile policing.

Glasgow, at the forefront of multi-agency efforts to improve city centre safety with its Nite Zone initiative, is expected to have a mobile medical unit giving first aid to late-night revellers this festive period.

It is believed on-the-spot treatment for pub and nightclub customers who have been injured would free up resources in the city's casualty units, notoriously hard-pressed at weekends.

The unit, which could also "baby-sit" drunks, mirrors a similar one in Cardiff, where ambulance crews have operated a designated city centre response vehicle for two years.

Mr MacAskill said: "Sadly, there's barely a weekend that goes by without one incident or another to remind us of the importance of tackling alcohol-fuelled violence.

"I hope the projects we're funding through this additional £1m can complement the Safer Scotland campaign to make the streets of our towns and cities safer and help people to have a more enjoyable Christmas and New Year.

"It is after all a time for enjoyment and celebration and it's important that we don't let the minority spoil the fun for everyone."

Meanwhile, following some criticism that Fife's test-purchasing scheme set out to entrap licensees, John Farrell, head of licensing at Strathclyde, said his force's approach would be "open and transparent".