ALMOST 160,000 children start smoking every year in the UK – enough to fill 5200 classrooms, a charity has warned.

Cancer Research UK said 157,000 children aged 11 to 15 take up the habit every year.

The charity, which backs a move to plain packaging for tobacco, says eight out of 10 people start smoking before they are 19 and more must be done to prevent youngsters starting.

The data refers to the proportion of children in an age group who were smoking a year after first saying they were smokers.

Almost a million under-15s (27% of all children) have tried smoking at least once. Among 12-year-olds, 1% were smoking regularly in 2009, 2% smoked occasionally and 2% said they used to smoke.

A year later, as 13-year-olds, 3% smoked regularly, 2% smoked occasionally and 4% used to smoke.

Jean King, Cancer Research UK's director of tobacco control, said: "Our research has shown that selling all cigarettes in standardised packs will help reduce the appeal of smoking."