There has been a renewed call for a tax on sugar – with the British Medical Association (BMA) suggesting 20% be levied on sugary drinks.

The organisation estimates poor diets are causing around 70,000 premature deaths each year – but it did not mention other sweet treats like biscuits and cakes.

The call by the BMA comes as the UK’s official Scientific Advisory Committee on Nutrition (SACN) prepares to publish its final advice on the amount of sugar we should be eating, which is due later this week.

In its Food for Thought report, the BMA warned a 330ml can of pop is likely to contain up to nine teaspoons of sugar that are simply “empty calories”.

The report said taxing specific food groups - such as the sugar drinks tax introduced in Mexico - were shown to cut consumption.

Professor Sheila Hollins, who led the team behind the report, said: “If a tax of at least 20% is introduced, it could reduce the prevalence of obesity in the UK by around 180,000 people.

“We know from experiences in other countries that taxation on unhealthy food and drinks can improve health outcomes, and the strongest evidence of effectiveness is for a tax on sugar-sweetened beverages.

“The majority of the UK population, particularly low-income households, are not consuming enough fruit and vegetables, so financial measures should also be considered to subsidise their price, which has risen by 30% since 2008.”

Elsewhere, The Daily Telegraph has reported that the SACN will say adults and children should be instructed by the government to halve the amount of sugar they consume and eat almost twice as much pasta, potato and other fibrous foods.

It is expected that the SACN will recommend 25g of sugar for women and 35g for men per day.