More than a quarter of children have tried smoking by the time they leave primary school, according to a study carried out in Liverpool.
Children are conditioned to become smokers at nursery age
Researchers from Liverpool John Moores University and The Roy Castle Lung Cancer Foundation carried out the study to find out why young people smoke.
The team spent 11 years interviewing 250 children from six schools, from reception class through to year six.
It found children as young as nursery age could be influenced to smoke.
The team behind the Liverpool Longitudinal Study on Smoking (LLSS) said they chose children from a range of socio-economic backgrounds to take part in the study.
They found that children from lower income families were more likely to start smoking.
They also found youngsters whose parents smoke were more likely to take up the habit than those whose homes were smoke-free.
But by the age of 11, the most important reason to take up smoking was to improve self-image, researchers said.
They will now follow the same group of children until they reach the age of 16 to complete the study.
Kevin Barron MP, member of the all-party group on smoking and health, said: "The younger children are when they start smoking, the more likely they are to carry on, and die early from the effects of this habit.
"It is shocking to think that children have experimented with smoking by the age of eight, but the results of this study highlight the seriousness of the situation."
Chris Owens, head of tobacco control at the Roy Castle Lung Cancer Foundation, said 450 young people started smoking every day in the UK, and more than half would die prematurely from a smoking-related illness.
Three children who took part will hand the results to Prime Minister Tony Blair on Friday. The findings will be presented to the Prime Minister as the government debates a public ban on smoking in the House of Commons.