New research has predicted that childhood obesity will soar over the next decade, overwhelming health services around the world.

The study by the World Obesity Federation says the number of children classified as obese will rise to around 250 million by 2030, up from 150 million today.

The organisation says the aggressive marketing of junk food is to blame, combined with lax government action.

The research suggests China and South Africa are likely to see the biggest increases.