A global study using World Health Organisation data has found that the greatest prevalence of inactive adults is in Malta (71.9%), followed by Swaziland at 69% and Saudi Arabia and Serbia (68.3%)

The people of Greece, Estonia and the Netherlands are the most active in Europe. 

By comparison, 40.5% of US citizens were inactive, despite more than 30% of them being obese. 

The study was led by Dr Pedro Hallal, from the Federal University of Pelotas in Brazil, who published the results in The Lancet medical journal.

Researchers collected date to compare 122 countries representing 89% of the world's population.

Inactivity was defined as not meeting any of three criteria: 30 minutes of moderate activity such as a brisk walk, at least five days a week; 20 minutes of vigorous activity at least three days a week; or an equivalent combination of the two.

The findings, part of a series of studies on physical activity, suggest that, worldwide, roughly three out of every 10 adults aged 15 and over do too little exercise.

Dr Hallal said: "Although the technical revolution has been of great benefit to many populations throughout the world, it has come at a major cost in terms of the contribution of physical inactivity to the worldwide epidemic of non-communicable diseases.

"Societal trends are leading to less not more activity than previously, and with few exceptions, health professionals have been unable to mobilise governments and populations to take physical inactivity seriously as a public health issue."

The research also found that more than 80% of 13 to 15-year-olds around the world do not get the minimum recommended hour of moderate exercise a day.

Lack of physical activity leads to 6% to 10% of all cases of heart disease, type-2 diabetes, and breast and bowel cancer.

Globally, it was responsible for around 5.3 million of the 57 million deaths that occurred in 2008.

The contribution of insufficient exercise to disease and shortened lifespan was similar to that of smoking or obesity. 

The estimates suggest that, worldwide, 6% of heart disease cases are linked to lack of exercise, ranging from 3.2% in south-east Asia to 7.8% in the eastern Mediterranean.

Low levels of physical activity are blamed for around 7% of type-2 diabetes cases, and 10% of breast and bowel cancer cases.