Teens are more likely to get hooked on cigarettes if their friends smoke and they feel alienated from school, new research shows.

Researchers in the U.S. used data from a survey of more than 20,000 teenagers to determine which influences made them most likely to starting smoking.

Teens who had at least two friends who smoked were more than six times as likely to become intermittent smokers than those whose friends didn't smoke.

These teens were also 10 times more likely than others to go from intermittent smoking to daily smoking.

"Peer smoking was by far the strongest predictor of smoking progression," said the study's lead author Elizabeth Lloyd-Richardson of Brown University in Providence, R.I.

Teens who were alienated from their school environment were 10 times more likely to start smoking than those who felt comfortable in school.

Alcohol was also a strong influence on teens to start smoking regularly, the study found.

However, parental smoking did not have a great influence on whether the teens started smoking. Teenage boys were not influenced at all by their parents, while teenage girls whose mothers smoked were 36 per cent more likely to start smoking.

Lloyd-Richardson said the research can be used to identify those students who would most benefit from smoking cessation programs.

"Teens that are already experimenting with smoking, are drinking alcohol, and have friends who smoke regularly should be targeted with interventions that halt the entrenchment of smoking," she said.

In Canada, 23 per cent of people aged 15 to 19 smoke regularly, even though it is illegal for people under the age of 19 to buy cigarettes.

The research appears in Monday's edition of the Journal of Clinical and Consulting Psychology.