A report by the foundation reveals that more than a third of children in England and Wales do not reach even minimum recommended exercise levels, with teenage girls being particularly inactive.

These statistics are worrying and we have to start doing something now

British Heart Foundation

Despite years of active campaigning to raise awareness of the risks, experts say the message is still not hitting home.

A spokeswoman for the British Heart Foundation said: "The premature death rate has been falling in recent years, but unless something is done about activity lessons for children it will begin to rise again.

"These statistics are worrying and we have to start doing something now."

Obesity is recognised as a growing problem among youngsters, who often spend hours in front of the TV or computer and have a passion for junk food.

Exercise campaign

To combat the problems which could lead to heart disease, the foundation recently launched its "Kids on the Go" campaign in a bid to promote the benefits of exercise for young people.

Health Education Authority guidelines recommend that children between the ages of five and 18 should take at least one hour of moderately intense activity - such as cycling, running, dancing or sports - every day.

Teenagers don't do enough PE at school

But primary schools in England and Wales have halved the amount of time allocated to physical education in the last five years.

Around 33% of boys and 38% of girls aged two to seven are not meeting minimum levels of activity.

And by the time they are 15, two thirds of girls do so little exercise that they are classified as "inactive".

Poor PE levels

Secondary schools in England and Wales fall behind their European counterparts.

Schools in France and Germany allocate three hours a week to PE classes, while in England and Wales the average secondary school has just two hours of lessons for pupils.

This means only a third of children in secondary schools get two or more hours a week of PE, compared to 46% in 1994.

The British Heart Foundation warns that unless habits are changed, the problem will be exacerbated in the future.

Coronary heart disease is still the most common cause of premature deaths (deaths under the age of 75) in the UK.

It accounts for 26% of premature deaths among men and 17% in women, with 147,000 people dying from the disease every year.