Sugar is so harmful that it should be controlled in the same way as tobacco and alcohol, according to a team of leading public health experts.

Three US scientists from the University of California at San Francisco (UCSF) maintain that sugar is more than just "empty calories" that make people fat.

They argue that high-calorie, sweetened food is indirectly responsible for 35 million annual deaths worldwide due to lifestyle-related conditions such as heart disease, diabetes and cancer.

Professors Robert Lustig, Laura Schmidt and Claire Brindis called for restrictions and controls on sugar that mirrored those on tobacco and alcohol.

The three set out their views in the leading science journal 'Nature'.

They pointed out that, at the levels consumed in the West, sugar altered metabolism, raised blood pressure, disrupted hormone signalling, and caused significant damage to the liver that was still not fully understood.

The health hazards were similar to the effects of drinking too much alcohol -- which was, in any event, manufactured from the distillation of sugar.

Prof Lustig, from the UCSF Benioff Children's Hospital, said: "As long as the public think sugar is just 'empty calories', we have no chance.

"There are good calories and bad calories, just as there are good fats and bad fats, good amino acids and bad amino acids and good carbohydrates and bad carbohydrates. But sugar is toxic beyond its calories."

Worldwide consumption of sugar has tripled in the last 50 years, fuelling a global obesity epidemic.

The main culprit is said to be fructose, a sugar molecule that is commonly added to processed food. There is increasing evidence that excess fructose has harmful effects on the body.

In their commentary, the experts proposed adding taxes to processed foods that contained any form of added sugar.

These would include carbonated drinks, other sugar-sweetened beverages such as juice and chocolate milk, and sugared cereals.

Other strategies included controlling access with measures such as age limits for the purchase of sugary drinks, and tightening controls on vending machines and snack bars in schools and workplaces.