Sixty-nine million children -- or more than one in five -- live in poverty in the world's 40 richest countries, UNICEF said in a report released Wednesday, blasting Britain and France for their particularly bad standings.

That's despite a drop in child poverty rates in the periods from 2012 to 2014 and 2019 to 2021, by around 8 percent in the 40 European Union and Organization for Economic Cooperation and Development (OECD) wealthy countries assessed.

"This is equivalent to around 6 million children out of a total child population of 291 million," said UNICEF Innocenti, the United Nations agency's research arm.

But at the end of 2021 there were still more than 69 million kids in poverty in those countries.

"For most children this means that they may grow up without enough nutritious food, clothes, school supplies or a warm place to call home," said Bo Viktor Nylund of UNICEF Innocenti, highlighting the impact of such struggles on young people's physical and mental health.

The UNICEF figure is based on relative poverty, which is around 60 percent of the national median income, often used in developed countries to establish their own poverty levels.

The report called for action to ensure children's well-being and for political will among the countries surveyed, stressing that a country's' wealth did not automatically lift its children out of poverty.

Since 2012, the biggest setbacks have been seen in some of the richest countries.

Britain saw a 19.6 percent jump in child poverty -- or half a million extra children, and France's rate went up 10.4 percent.

In the United States, the number of poor children has fallen by 6.7 percent, but more than one child in four still lives in relative poverty.

And the poverty rate in 2019-2021 was twice as high as in Denmark, a country with a similar per-capita income.

Underlining the link between child poverty and economic inequality, the report also highlights the greater risk of poverty for children from single-parent families and minority backgrounds.

In the United States, 30 percent of African American children and 29 percent of Native American children live below the national poverty line, compared with only one-in-10 non-Hispanic white children.

In the EU, a child with parents of non-EU nationality is 2.4 times more likely to live in poverty.