Aggressive and anti-social boys are often popular with their classmates, says a study.

While teachers and parents might disapprove of their behaviour, disruptive boys are "rewarded" with the approval and admiration of their peer groups.

And researchers are concerned that an association between aggression and popularity can have long-term risks - with playground aggression developing into adult violence.

A study by psychologists of over 450 primary school boys in Chicago and North Carolina found that bad behaviour made some pupils more popular rather than less.

While "model" pupils, who were well-behaved and good at lessons and sport, were among the most popular, researchers found that a third of very popular pupils were "extremely anti-social".

These boys would start fights, disrupt lessons, act aggressively and regularly get into trouble - but would remain popular with other pupils,

'Potentially dangerous'

The significance of this, says researcher Philip Rodkin of Duke University, is that in later years it can be difficult to make these boys adjust their behaviour, when they have made a connection between being anti-social and gaining popularity.

"These boys may internalise the idea that aggression, popularity and control naturally go together, and they may not hesitate to use physical aggression as a social strategy because it has always worked in the past.

"There will come a point in these boys' lives when this turns from an adaptive and fun characteristic, to a lonely and potentially dangerous one," said Dr Rodkin

The study, published in Developmental Psychology, is based on research in urban, suburban and rural schools, carried out by academics from the University of North Carolina, University of Illinois and Duke University.