The number of people suffering from hunger has increased during the past three years, after years of decline, a UN report suggests.

According to the analysis, 821 million people globally were undernourished in 2017 - about one person in every nine.

And nearly 151 million under-fives - 22% of the global total - have their growth stunted by poor nutrition.

The authors say extreme climate events are partly to blame for the rise and call for urgent global action.

The report, The State of Food Security and Nutrition in the World, also says difficulties accessing nutritious food is contributing to the growing problem of obesity in the world, with one in eight adults - more than 672 million - being classified as obese.

'Complex and frequent'

The authors note the frequency of extreme climate events - floods, heat, storms and droughts - has doubled since the early 1990s.

And they say: "The report sends a clear message that climate variability and exposure to more complex, frequent and intense climate extremes are threatening to erode and even reverse the gains made in ending hunger and malnutrition."

Climate extremes have a direct impact on crop yields and food availability but can also reduce:

• the number of fit and healthy people available to grow and harvest crops
• the time and money people have to find nutritious and safe food

And hunger is significantly worse in countries where agricultural systems are sensitive to variations in rainfall and temperature and where many people depend on agriculture for their livelihoods.

'Urgent help'

The authors say: "Climate variability and extremes - in addition to conflict and violence in this part of the world - are a key driver behind the recent rises in global hunger and one of the leading causes of severe food crises."

And they call for coordinated global and local action so countries become more resilient to climate-related disasters.

Commenting on the report, Robin Willoughby, from Oxfam, said: "It is shocking that after a prolonged decline, this is the third consecutive year of rising hunger.

"The inescapable fact is that climate change is now leaving people around the world without enough to eat.

"Hunger is significantly worse in countries hit by severe droughts and flooding. A hotter world is proving to be a hungrier world.

"The people behind these stark statistics need urgent help. Our political leaders must redouble efforts to cut the use of fossil fuels and commit funds to help poor countries adapt to climate crises."

The report was compiled by the Food and Agriculture Organization of the United Nations, the World Food Programme, Unicef, the World Health Organization, and the International Fund for Agricultural Development