At least 41 million children under the age of five are obese or overweight across the globe, with numbers rising most rapidly in developing countries, the World Health Organisation (WHO) said on Monday.

The number of obese or overweight children has risen by 10 million worldwide since 1990 and there are now more overweight and obese children in low- and middle-income countries than in high-income countries, the WHO said.

In developing countries, the number of overweight children more than doubled to 15.5 million in 2014 from 7.5 million in 1990, driven by globalisation and urbanisation, a report by the WHO Commission on Ending Childhood Obesity (ECHO) said.

"Overweight and obesity impact on a child's quality of life, as they face a wide range of barriers, including physical, psychological and health consequences," Sania Nishtar, ECHO co-chair, said in a statement.

"We know that obesity can impact on educational attainment too and this, combined with the likelihood that they will remain obese into adulthood, poses major health and economic consequences for them, their families and society as a whole."

The marketing of unhealthy food and drinks was the major factor in the increase in numbers of overweight and obese children, particularly in the developing world, the WHO said.

Almost half of overweight and obese children under five live in Asia and 25 percent in Africa, where the number of overweight children almost doubled to 10.3 million in 2014 from 5.4 million in 1990, the WHO said.

It said Libya, Egypt, Morocco, Algeria, Tunisia and Botswana had the highest percentage of overweight children among African countries.

Children who don't have access to enough nutritious food in early childhood are at an particularly high risk of becoming obese when their food intake and activity levels change, the WHO said.

And children of migrants and indigenous people were also at a higher risk of becoming obese due to rapid cultural changes and limited access to healthcare.

The report said that obesity epidemic had the potential to reverse many health gains across the globe and called on governments to address what it called a major health challenge.

"WHO needs to work with governments to implement a wide range of measures that address the environmental causes of obesity and overweight, and help give children the healthy start to life they deserve," said Peter Gluckman, ECHO co-chair.

Among its recommendations, the WHO said governments should promote healthy foods, physical activity and healthy school environments.  - Thomson Reuters Foundation