People should cut their sugar intake in half if they want to reap health benefits, the World Health Organisation (WHO) has said.

Current WHO guidelines say sugars should make up less than 10% of total energy intake per day for adults and children but experts believe slashing this to 5% is more "ideal".

In new draft guidelines, which are subject to consultation, the WHO maintains its original advice that sugars should be less than 10% of total energy intake per day.

But it argues that cutting this intake to less than 5% would bring "additional health benefits" and is the figure people should aim for.

For adults of a normal weight, this would mean cutting intake from around 50g - about 12 level teaspoons - of sugar per day to less than 25g.

Health experts backed the move but called on WHO to make the 5% an official recommendation.

They also criticised the UK Government's responsibility deal with the food and drinks industry, which sees companies such as chocolate manufacturers signing up to voluntary codes.

The WHO's limits on intake of sugars apply to all monosaccharides (such as glucose, fructose) and disaccharides (such as sucrose or table sugar).

These are added to food by the manufacturer, the cook or the consumer, and are also sugars that are naturally present in honey, syrups, fruit juices and fruit concentrates.

The WHO said much of the sugars consumed today are "hidden" in processed foods such as sweets, with sugary fizzy drinks having about 10 teaspoons of sugar.

The new guidelines follow several studies on the impact of sugar on obesity and dental cavities.

Dr Francesco Branca, director for nutrition for health and development at the WHO, told a news conference that the 10% target was a "strong recommendation" while the 5% target was "conditional", based on the evidence.

He added: "Five percent is the ideal one and the 10% is the more realistic one.

"We have few countries (hitting) below 10%. But, yes, we should aim for 5% if we can."

Dr Branca said obesity affects half a billion people around the world and is on the rise among all age groups.

He said the recommendation for less than 5% was important because it told countries that reductions to "below 5% are even better".

Announcing the revisions, the WHO said in a statement: "WHO's current recommendation, from 2002, is that sugars should make up less than 10% of total energy intake per day.

"The new draft guideline also proposes that sugars should be less than 10% of total energy intake per day.

"It further suggests that a reduction to below 5% of total energy intake per day would have additional benefits."

The news comes after England's chief medical officer, Professor Dame Sally Davies, told MPs yesterday that a "sugar tax" may have to be introduced to curb child and adult obesity.

She said being overweight had become "normalised" in Britain and the Government should regulate the food and drinks industry to protect people against the dangers of excess calorie consumption.

"We need to be both strong and prepared to regulate. I think that the science is going such that that we will find sugar is addictive," she said.

"We haven't managed to get over to the public how calorie packed fruit juices are, smoothies are, colas and carbonated drinks. We need to have a big education to know one is fine, but not lots of them.

"We may need to move to some sort of sugar tax, but I hope we don't have to."

Asked if the Prime Minister was ready to consider introducing new laws or taxes to cut sugar consumption, David Cameron's official spokesman said yesterday: "The Prime Minister's view is that the significant things the Government is doing through the responsibility deal with industry is the right way to be going about this, because at the heart of this is ensuring people have the public health information."

Today, Action on Sugar - a group of experts and academics in obesity, health and nutrition - called on the WHO to make its official recommendation less than 5%.

The NHS currently recommends added sugars make up no more than 10% of calorie intake from food and drink each day.

Action on Sugar chairman Professor Graham MacGregor; said: "Added sugar is a completely unnecessary part of our diets, contributing to obesity, Type 2 diabetes and tooth decay.

"We strongly urge the WHO to recommend reducing sugar intakes to below 5% daily calories, as this will have the biggest impact on our health.

"We have known about the health risks of sugar for years and yet nothing substantial has been done - new recommendations will be a wakeup call to the Department of Health and the Government to take action on sugar now by forcing the industry to slowly reduce the huge amount of sugar added by the food industry across the board.

"Setting targets for sugar reduction will not rely on the industry-determined responsibility deal calorie pledge, which has had no measurable effect on calorie intake.

"Unless they act now, obesity and diabetes are going to completely overwhelm the NHS."

Simon Capewell, professor of clinical epidemiology at the University of Liverpool, UK, said: "A 5% target would reflect extensive scientific evidence linking excess sugars with obesity, diabetes, heart disease and common cancers (and rotten teeth in kids).

"Brits currently consume about three times too much sugar, 15% not 5%.

"This is because of the huge amounts of added sugars hidden in most processed foods: soups, yoghurts, ready meals, sugary drinks, fruit juices and smoothies.

"The UK Government and the industry have a clear duty to slash the sugars hidden in these foods, to protect our kids."

He said taxes on sugary drinks were working in the USA, France, Hungary and Finland.

Science director of Action on Sugar, cardiologist Dr Aseem Malhotra said: "I fully welcome the calls for the WHO to recommend intakes to be reduced to 5%, but this needs to be translated into something meaningful.

"In particular, consumers need to know how much sugar is being added to processed foods, which currently isn't the case."