Vending machines selling crisps, chocolate and fizzy drinks should be banned from schools in an effort to promote healthier lifestyles in children, according to a opinion poll organised by the Guardian newspaper.

Nearly seven in 10 adults supported the measure, and there was also significant backing for an end to advertising aimed at children by fast food companies.

The results come as the government's Food Standards Agency prepares to launch a national debate on the role of advertising and promotions by companies.

It has been suggested that schools should run experiments, offering fruit juices in vending machines instead of fizzy drinks.