Washington, March 21 (IANS): Suspending kids from school for using marijuana is likely to lead to more - not less - pot use among their classmates, a study has found.

Students attending schools with suspension policies for illicit drug use were 1.6 times more likely than their peers at schools without such policies to use marijuana in the next year - and that was the case with the student body as a whole, not just those who were suspended, the findings showed.

The study published in the American Journal of Public Health showed that counselling was a much more effective means of combating marijuana use.

"That was surprising to us," said co-author Richard Catalano, professor at the University of Washington.

"It means that suspensions are certainly not having a deterrent effect. It is just the opposite," Catalano added.

The researchers found that students attending schools with policies of referring pot-using students to a school counsellor were almost 50 percent less likely to use marijuana.

Data for the research came from the International Youth Development Study, a long-term initiative started in 2002 to examine behaviour among young people in Washington and Victoria.

The two states were chosen since they are similar in size and demographics, but differ considerably in their approaches to drug use among students.

Washington schools are more likely to suspend students, call police or require offenders to attend education or cessation programmes, the researchers said, while Victoria schools emphasise a harm-reduction approach that favours counselling.

Researchers surveyed more than 3,200 seventh and ninth-graders and nearly 200 school administrators.