In a bid to combat obesity, the World Health Organisation is pushing for a big drop in the consumption of "hidden" sugar in food and drinks.

The World Health Organisation has urged a dramatic drop in the consumption of sugar, "hidden" in everything from soft drinks and tomato sauce, as it steps up the fight against obesity.

The UN health agency had previously issued guidelines that sugars should make up less than 10 per cent of a person's total daily energy intake, but in a new twist, has urged countries to strive for half that.

Setting the bar at five per cent would mean people should consume no more than 25 grams, or the equivalent of six teaspoons of sugar a day - less than the 10 teaspoons in your average can of soft drink.

Health-hazardous free sugars, in the form of table sugar, fructose or glucose for instance, are added to foods and drinks by manufacturers, cooks and consumers themselves, and are naturally present in substances like honey and fruit juices.

The guidelines issued on Wednesday do not refer to sugars in fresh fruits, vegetables and milk, since there is no evidence they are harmful, WHO said.

The UN agency pointed out that much of the so-called free sugars consumed today are "hidden" in processed foods that are not usually seen as sweet, like tomato sauce, which contains a full teaspoon of the sugar in each tablespoon.

WHO has for more than a decade recommended keeping sugar consumption below 10 per cent of a person's total daily energy intake - a target it considers clearly supported by scientific evidence which countries should adopt as policy.

But the UN health agency decided to halve the previous recommended level following a year of discussions among WHO member states.

The five per cent recommendation, however, remains "conditional", WHO said, since too few epidemiological studies have been carried out in populations with such low sugar intake to allow a clear comparison.