The study, based on interviews with nearly 10,000 pupils, found lessons on drugs and cigarettes may have no impact.

Drugs education is a statutory part of the national curriculum for pupils from the age of five but only 66 per cent of pupils surveyed could recall lessons on the subject.

The National Centre for Social Research and the National Foundation for Educational Research also said it “cannot be inferred that lessons lead to lower rates of smoking or drug use”.

The study commissioned by the Department of Health found a slight link between the proportion of 15 and 16-year-olds who remembered lessons on smoking and those who smoked.

Of the Year 11 pupils who did remember the lessons, 22 per cent smoked, compared to 28 per cent who did not. Similar data was also found for cannabis use by teenagers in Years 9, 10 and 11.

However, the researchers did not find such links for children in younger age groups and said that the relationships between lessons and drug use were unclear because of other factors.

Pupils who played truant or were excluded were more likely to take drugs and smoke and more likely to have missed drugs lessons because they were not in school.

Other findings included a drop in the proportion of 11 to 15-year-olds taking drugs from 20 per cent to 18 per cent.

The fall was applauded by the drugs advisory group AdFam which said it showed drug education policies were leading to improvements.

But Mary Brett, a biology teacher and lead member of the National Drug Prevention Alliance, said drugs lessons were ineffective because they placed too much emphasis on “choices” rather than prevention.

“Smoking, Drinking and Drug Misuse Among Young People in England in 2002” is at www.doh.gov.uk