Health campaigners are urging the government to introduce a new “calorie tax” to tackle childhood obesity, diabetes and cancer.

A levy on companies producing processed food with high levels of fat and sugar would encourage them to create more nutritional snacks, according to campaign groups Action on Sugar and Action on Salt.

Their call for further tariffs, which is backed by the Liberal Democrats, comes after Boris Johnson vowed during the Tory leadership campaign to freeze so-called “sin taxes”, which include levies on alcohol, tobacco and soft drinks.

The existing sugar tax has been widely praised by doctors and health experts but campaigners want to go further by targeting sweet, fatty foods such as chocolate confectionery, ice creams, puddings, chocolate spreads and milk-based drinks.

Katharine Jenner, campaign director for Action on Sugar and Action on Salt, said: “Manufacturers are simply not doing enough. If the Government is really committed to helping the less well-off, they need to tackle the food industry and a feasibility study needs to be undertaken without delay.

“An ‘excess calorie levy’ would encourage manufacturers to improve the nutritional quality of their unhealthy foods and, most importantly, tackle the thousands who suffer the consequences of a poor diet, leading to obesity, Type 2 diabetes and cancer.”

The amounts of sugar in food and drink Show all 6 1 /6 The amounts of sugar in food and drink The amounts of sugar in food and drink Minstrels A 42g bag contains 28.9g of sugar The amounts of sugar in food and drink Dairy Milk A 49g bar contains 26.8g of sugar The amounts of sugar in food and drink Skittles 45g of Skittles (about a quarter of a large 174g pouch) contains 40.4g of sugar The amounts of sugar in food and drink Ribena A 500ml bottle of Blackcurrant Ribena contains 23g of sugar, down from 50g/500ml after it was reformulated to avoid the government's tax on sugary drinks The amounts of sugar in food and drink Coca Cola A 330ml can of Coca Cola contains 35g of sugar The amounts of sugar in food and drink Innocent Smoothies A 250ml bottle of strawberries & bananas Innocent Smoothie (the middle size) contains 26g of sugar

The tax on sugar in soft drinks is said to have taken 90 million kilos of sugar out of the nation’s diet since it was introduced in April 2018.

Graham MacGregor, professor of cardiovascular medicine at Queen Mary University of London, and chairman of Action on Sugar and Action on Salt, said it was imperative that the tax continued.

“The UK Soft Drinks Industry Levy has been remarkable and unique in that it allows for significant product reformulation by manufacturers in order to avoid paying the levy,” he said.

“This has already resulted in a much bigger reduction of sugar content of drinks in the UK than originally anticipated, as well as ring-fencing £340 million of income directly from manufacturers, not the public, to spend on improving children’s health.

“Additionally, the same could be achieved in creating a levy to reduce excess calories, but we need a firm commitment from HM Treasury and the Department of Health and Social Care to make this a reality and to implement a robust evaluation system to fill in the evidence gaps.

“This levy should be invested back in a much more comprehensive approach to prevent obesity in both children and adults.”

Liberal Democrat health spokesperson Judith Jolly said she supported calls for a government levy on companies producing food with excessive calories.

“With rising rates of obesity for children, which leads to higher rates of health problems in the future such as type 2 diabetes, heart disease and certain cancers, more needs to be done to improve the health outcomes for our children.

“Manufacturers should be doing more to reduce excessive levels of calories in unhealthy food. Instead of holding them to account however, Boris Johnson is happy for companies to keep earning profits on products with hidden and addictive sugar at the expense of children’s health. Liberal Democrats demand better.”

The Department of Health and Social Care said in a statement there were “no plans to introduce a calorie levy”.

“We are already reducing exposure to fatty and sugary foods, and are now consulting on further plans to offer clear labelling and more support for individuals to manage their weight,” a spokesperson added.

Details of its review of the tax on sugar in soft drinks are “still being worked out”, according to the department, and it remains unclear whether this will be in addition to the expert review funded by the National Institute for Health Research.

Last month it published a green paper consultation document containing proposals to ban the sale of energy drinks to under-16s and extend the sugar tax to milkshakes.

The issue has divided Conservative ministers. When Liz Truss, a prominent Johnson supporter, claimed that scrapping the tax would “help Britain’s poorest”, health minister Caroline Dineage responded with the word “bollocks”. Former public health minister Steve Brine vowed to rebel against any attempt to abolish the levy.

Professor MacGregor said it was “scandal” that Mr Johnson was questioning the effectiveness of taxes on food and drinks products.

However the Food and Drink Federation, which represents the food industry, claimed taxes were far less effective than other measures such as portion control and product reformulation.

Tim Rycroft, FDF chief operating officer said: “At the moment the industry is focused on trying to prevent food shortages and rising food prices in the case of a no-deal Brexit.

“The industry is working hard to implement what has already been asked of them in the three Childhood Obesity Plans that have been published in just three years.

“There is no evidence that additional food taxes can change consumer behaviours over the long-term. Food and drink companies should focus efforts where they can have the maximum impact, instead of managing the impact of wrong-headed legislation.”