DRUG gangs are using children as young as 12 to import heroin and other Class A drugs into Scotland after police successes in disrupting traditional delivery routes and crime syndicates.

Children and vulnerable adults are being used as "mules" to bring in the drugs. Kids are even distributing heroin on bicycles.

In a ground-breaking study academics from the University of the West of Scotland, the University of West London and the Metropolitan State University in Minnesota interviewed 43 present and former high-level criminals to map the changes.

They discovered that, in a variant of what is known as "county lines" – where established gangs spread from their normal operating areas in big cities to exploit new markets – children are travelling by bus and train to transport drugs and traffic them using dedicated mobile phones, or "lines".

The charity Action for Children Scotland has seen at first-hand how it works and how children are enrolled in organised crime. Director Paul Carberry said: “It is a sad fact of life that a number of children and young people are groomed from an early age by serious criminals, with boys being asked to deliver drugs on their bikes. In Glasgow, we run the only serious organised crime early intervention service of its kind in the UK working with young people on the cusp of organised crime.

"One young boy we supported was selling heroin from the age of 14. He didn’t take the drug, but he made money from selling it in his local community. The money he did make was spent on other drugs for himself, but the larger profit was made by the people who he was working for. However, the most damaging impact was felt by the local community that found itself ravaged by the effects of an influx of drugs."

According to Carberry children are enlisted through their family.

“Many of the children and young people we support are involved in crime because their family is also involved," he said. "It’s not unusual for this to span back generations and we have worked with young people whose grandparents are involved in drug dealing at a higher level than the young people."

The academic paper on changes to the Scottish drug markets also identified a major new supply line for heroin through Northern Ireland, augmenting the traditional routes from Liverpool and Manchester. Since the 1998 Good Friday Agreement there has been a significant rise in trafficking by former paramilitaries helped by the proximity of the Scottish west coast and the lucrative drug market just 12 miles across the sea.

Recent police operations have severely disrupted organised crime gangs. In January a nine-man cocaine syndicate, with links to the Glasgow crime family the Daniels, were jailed for a total of 87 years. One of them, former soldier Martyn Fitzsimmons, supplied British Army explosives to the Daniels. Since 2001 the clan has been at war with the Lyons crime family, with tit for tat shootings and stabbings.

Fitzsimmons went down for 10 and a half years after admitting having a Glock hand gun and ammunition and hiding £36,000 of drug proceeds. Less than two months before he had been cleared of shooting Lyons enforcer Ross Monaghan outside St George's primary school in Glasgow. Two months ago he was slashed and suffered horrific injuries in a targeted attack at Low Moss prison outside Bishopbriggs.

The Scottish drug market is now in a state of flux. Mobile phones and the internet have led to a diversification with online apps and social media platforms used to distribute, including a 24-hour "dial a deal" delivery to a buyer's front door.

As the academic study discovered: "The internet not only enabled respondents to source drugs from further afield, it also fed consumer demand for new illicit products such as steroids or new psychoactive substances."

Another development used by dealers to minimise risk is known as "cuckooing", pressuring young people into holding drugs and selling from their houses, or, if a vulnerable or indebted adult, their house is taken over as an operational base.

Most of the heroin and cocaine on Scottish streets comes from the coca plantations of South American and the poppy fields of Afghanistan or Pakistan, through England and one of four national hubs, London, Birmingham, Liverpool and Manchester. It is then delivered in smaller batches to gangs north of the Border, often with deadly results.

According to the latest-available figures there were 867 drug-related deaths in Scotland in 2016, a 23 per cent rise on the previous year and almost double the figure for 2006. Almost one-in-three of the deaths was in the Great Glasgow and Clyde health board area. And around 90 per cent of the overall deaths were from heroin, morphine and methadone.

The illicit drug business, and its effects, now know no frontier. As James Densley, the lead researcher from the Metropolitan State University puts it: "But what was interesting to us was this idea that in a global world that the traditional borders don’t apply any more."