More than 821 million people suffered from hunger worldwide last year, the United Nations reported Monday - the third year in a row that the number has risen.

After decades of decline, malnutrition began to increase in 2015, mainly because of climate change and war. Reversing the trend is one of the 2030 targets of the UN's Sustainable Development Goals which aim to improve the planet and its people.

But getting to a world where no one is suffering from hunger by then remains an "immense challenge," the report said, noting the number of people without enough to eat had risen from 811 million in 2017. 

"We will not achieve zero hunger by 2030," said David Beasley, head of the World Food Programme, one of the UN agencies contributing to the report. 

"That's a bad trend. Without food security we will never have peace and stability," said Beasley, deploring that the media carry more talk about Brexit and US President Donald Trump than children dying of hunger.

He warned that extremist groups were using hunger and control over food supplies as a weapon to divide communities or recruit new members.

"The State of Food Security and Nutrition in the World" report was produced by the UN Food and Agriculture Organization (FAO) and other United Nations agencies including the World Health Organization.  

"To safeguard food security and nutrition, it is critical to already have in place economic and social policies to counteract the effects of adverse economic cycles when they arrive, while avoiding cuts in essential services, such as healthcare and education, at all costs," it said.

A "structural transformation" was needed to include the poorest people in the world, the authors said.

This would require "integrating food security and nutrition concerns into poverty reduction efforts" while tackling gender inequality and the exclusion of certain social groups, they said.

Malnutrition remains widespread in Africa, where around 20 percent of the population is affected, and in Asia where more than 12 percent of people experience it. In Latin America and the Caribbean, fewer than seven percent of people are affected.

Adding those hit by food insecurity gives a total of more than two billion people, eight percent of whom are in North America and Europe, who don't regularly have access to enough nutritious, safe food, the report said.