Britain would need to put a 20 per cent "fat tax" on unhealthy food and drink to improve the numbers of people suffering diet-related conditions such as obesity and heart disease, medical experts warn.

Such a move should be combined with subsidies on healthy foods such as fruit and vegetables, said academics on

The group released their findings ahead of the 65th World Health Assembly in Geneva on May 21 to May 26, where prevention and control of non-communicable diseases will be key issues for discussion.

Dr Oliver Mytton and colleagues at the University of Oxford said evidence suggests taxing a wide range of unhealthy foods is likely to result in greater health benefits than "narrow taxes" - although the strongest evidence related to taxing sugary drinks.

They said one American study found a 35 per cent tax on sugar-sweetened drinks in a canteen led to a 26 per cent decline in sales.

Studies extending VAT on unhealthy foods in the UK could cut up to 2,700 heart disease deaths a year, the researchers said.