Researchers looked at how much offenders drank

They found that, on average, young men convicted of murder started drinking aged 12, compared to age 15 in a group of young burglars.

Those who committed violent crimes also reported drinking over twice the amount that non-violent offenders drank.

Researchers told the Faculty of Child and Adolescent Psychiatry conference that policy makers should investigate the link.

Cause and effect may work in both directions Andrew McNeill, Institute of Alcohol Studies

They said drinking early and heavily could be a marker for later violent behaviour that should be examined.

Drug abuse

The researchers talked to 21 young male offenders convicted of murder in the UK before the age of 18 and 21 non-violent burglars in prison.

They were asked how old they were when they first drank and took drugs, how much they had drunk per week and the amount of drugs they had taken.

All the murderers and 18 burglars said they had used alcohol before they were sent to prison.

But those in the group convicted of murder had begun drinking earlier, on average 12.3 years of age, compared to 15.5 years old in the burglar group.

The average number of units consumed per week was 64.3 among the murderers and 24.2 among the burglars.

In both groups, about 70% used cannabis daily or weekly.

The researchers say other studies have shown that alcohol has harmful effects on the developing brain.

'Delinquent'

They said: "If policy-makers are to introduce effective programmes to reduce juvenile violence, we need to understand the contributing factors.

"These findings underline the need to develop mechanisms for early detection and effective intervention in this highly vulnerable group of young people."

Andrew McNeill, director of the Institute of Alcohol Studies, told BBC News Online: "Young children who are delinquent, who are increasingly behaving violently, are more likely to become problem drinkers."

He said the research linking violence and alcohol was interesting, though it was a small study.