LONDON — Young male soldiers who have served in Iraq or Afghanistan are more likely to commit violence offences than their older or civilian counterparts, a British study published Friday said.

In the largest study of its kind to date, researchers for the Lancet medical journal interviewed almost 14,000 British servicemen and women and examined their criminal records.

The most significant finding was that 20.6 per cent of male soldiers aged under 30 had been convicted of a violent offence, compared with 6.7 per cent of civilian men in the same age group and 11 per cent of all military men.

Young men involved in direct combat were 53 per cent more likely to commit a violent offence, said the study, which comes ten years after the start of the Iraq war.

Violence was also connected with post-traumatic stress disorder, being in the lower ranks of the army, a previous history of violence and alcohol abuse.

Simon Wessely, who co-authored the study, told journalists in London that it was not a bad thing for soldiers to have an aggressive streak.

"Some people with aggressive dispositions make very good soldiers, that's the nature of the game," he said.

"My own view, and the view of many people in this area, is that you meet a lot of people in the armed forces who you're glad are in the armed forces, and it's doing them a lot of good."

He emphasized that most soldiers returning from duty were not likely to offend.

"We are suggesting there is a problem that needs to be looked at, but just as with post-traumatic stress disorder this is not a common outcome in military populations. Overall, you must remember that of those who serve in combat, 94 per cent of who come back will not offend," he said.

