Over 20% of children, or 69 million, grapple with poverty across the 40 wealthiest nations, UNICEF said in a report released Wednesday, criticizing Britain and France for their poor standings.

That's despite a drop in child poverty rates in the periods from 2012 to 2014 and 2019 to 2021, by around 8% in the 40 European Union and Organisation for Economic Co-operation 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% 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% jump in child poverty – or half a million extra children, and France's rate went up 10.4%.

The U.K. ranked 39 out of 39 relatively well-off countries.

"Poverty experienced anywhere and in any form poses risks to children's health, well-being, and development. The consequences can last a lifetime and tackling it should be a national priority," said Jon Sparkes, chief executive of the United Kingdom Committee for UNICEF.

"While some countries in this group have taken steps to increase support, in the UK we have seen a reduction in spending on child and family benefits and more children growing up in poverty as a result," Sparkes noted.

The report said that during the period it focused on, U.K. expenditure on family cash benefits per child, as a proportion of gross domestic product (GDP) per capita, decreased from 18% to 11%.

It said several changes to targeted financial support had contributed to this, including the benefit cap, limiting the benefits a household earning below a set threshold can receive, and the two-child limit for child tax credits and the child element of Universal Credit, meaning families cannot claim support for more children.

"We urge the U.K. Government to take steps to protect all children from poverty, starting by making child poverty reduction a Government priority, scrapping the two-child limit policy and benefits cap and improving services and support, especially for the youngest children through a national baby and toddler guarantee for all children in the U.K.," said Sparkes.

A spokesperson for the Department for Work and Pensions said: "There are 400,000 fewer children and 1.7 million fewer people in absolute poverty when compared to 2010."

"But we understand some families are still struggling. This is why we have worked hard to halve inflation and are providing on average 3,700 pounds ($4,670) per household to help with the cost of living, including increasing benefits by over 10% this year."

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

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% of African American children and 29% 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.