FAST food could be behind surging rates of allergies and asthma among children, an international study has found.

Scientists from New Zealand, Spain, Australia, Germany and Britain found young teenagers, in particular, are nearly 40 per cent more likely to have severe asthma if they eat burgers and other types of fast food more than three times a week.

Scientists found young teenagers, in particular, are nearly 40 per cent more likely to have asthma if they eat fast food more than three times a week.

They say their study could have ''major public health significance owing to the rising consumption of fast foods globally'' if the link turns out to be causal.

The study has the potential to overturn the so-called ''hygiene hypothesis'' - that our obsession with cleanliness is behind the rise in allergic conditions around the world.