Healthy meals offered by fast-food chains are not as healthy as they are believed to be, an Australian analysis has found.

Public health experts have said the research reinforced calls for a junk-food tax, with research also showing a tax would be more effective than promoting healthy eating and exercise.

According to the study less than half the salads available at fast-food outlets were low fat but there was a twentyfold variation in sugar and fat between salads.

The study took into consideration nearly 90 percent of Australian fast-food outlets.

The study found not even a single sandwich to be low-salt,.