The food industry has been handed an ultimatum to help improve Scotland's eating habits or face a sugar tax.

Food Standards Scotland (FSS), a new body set up to advise the Scottish Government on nutrition, said officials should be working with experts to plan a levy on sugary products including the rate to set.

They advise offering retailers and manufacturers 12 months to come up with alternative ways to combat the quantities of sweet food and drink which Scots purchase.

These could include switching money-saving promotions to healthier products, reducing the size of sweet treats and reviewing recipes to make items healthier.

Other organisations including the Royal College of Physicians and Surgeons of Glasgow have backed the call to action.

However, responding to the proposals, Public Health Minister Maureen Watt said the Scottish Government was already "taking a range of actions to improve diet" and "have no plans to introduce a sugar tax".

If obesity continues to rise at the current rate 40 per cent of the Scottish population will be obese in 15 years, according to the FSS.

Their board have agreed a raft of radical measures to try to halt this trend, which they intend to put to the Scottish Government.

The proposals say they should recommend to ministers that government and FSS officials "actively consider how a sugar tax may be introduced and at what rate."

They suggest giving "industry a 12 month period to come up with an alternative acceptable solution to a sugar tax to reduce sugar purchase from current levels."

FSS board chairman Ross Finnie said it was disappointing if such measures were not going to be considered by ministers adding that Scotland has among the highest levels of obesity in the world. He said: "The only reason we have come to the conclusion we should explore either regulation or taxation is because the record of voluntary measures shows we are simply not making the progress we need to make."

In Mexico, studies have shown a 10 per cent tax has reduced the purchase of sugar-sweetened soft drinks by 12 per cent.

The Scottish Parliament could vote to introduce a tax based on sugar content, but it would need approval from Westminster to introduce the policy.

Ministers are said to be concerned such a move could spark a similar legal wrangle to the bid to set a minimum price for alcohol.

Ms Watt said: “We have no plans to introduce a sugar tax – and in any case, we do not currently have the direct power to do so. However, we are grateful to Food Standards Scotland for undertaking this work on a key public health issue and will consider their report.

“We are also examining what further effective actions we can take within the current powers of the Scottish Government that would have an impact on obesity rates, including on the use of multi-buy promotions. Food Standards Scotland will be an important partner in this on-going work and we look forward to continuing to work with them to drive forward our shared agenda of making Scotland healthier.”

David Thomson, chief executive officer for the Scottish Food and Drink Federation, said the industry had a strong record for making changes voluntarily around salt content and portion sizes.

He continued: "Punishing and legislating against an industry that employs 34,000 people in Scotland – 19 per cent of all our manufacturing jobs – would be a retrograde step, in particular when there is no evidence of the long-term effectiveness of additional taxes on single nutrients, foods or drinks. Instead, Food Standards Scotland and the Scottish Government should work with industry in partnership to make a real and effective difference for Scotland’s people.”

Lorraine Tulloch, of Obesity Action Scotland, said: “We are facing a public health crisis with overweight and obesity in Scotland. The steps that the FSS board has agreed today have significantly shifted the debate on regulation and taxation of unhealthy food to when and how it should happen.”

Professor David Galloway, president of the Royal College of Physicians and Surgeons of Glasgow, said: "Food Standards Scotland and Obesity Action Scotland have proposed direct measures to tackle the problem head on. We have a real opportunity in Scotland to demonstrate global leadership and deliver meaningful change for the benefit of current and future generations."