The United Nations Children's Fund says more than a quarter of children under the age of 5 worldwide are permanently "stunted" from malnutrition, leaving them physically and intellectually weak and representing a scandalous waste of human potential.

Anthony Lake, executive director of UNICEF since 2010, said organized provision of vitamins and clean water and a focus from birth on breastfeeding could have helped these 165 million children achieve normal brain and body development. But their lack of proper nutrition means instead they will suffer increased vulnerability to illness and early death.

"Stunting is the least understood, least recognized and least acted upon crisis. It is a hidden crisis for these children," said Lake, a veteran U.S. diplomat who was national security adviser to President Bill Clinton in the 1990s.

Lake said the failure to give children enough Vitamin A, iron and folic acid when developing in the womb, and a balanced diet with clean drinking water in the first 2 years of life, doomed most of them to being anchors on their impoverished societies.

"Stunted doesn't mean simply short," Lake told The Associated Press in an interview. "The child's brain never properly develops. Irrevocably. That's it. You can't fix it later. You can fix being underweight. You can't fix being stunted after age 2."

Lake was in Dublin to unveil the findings in a report at a global conference focused on combating hunger and malnutrition. He showed slides of CAT scans of stunted children's brains, with weaker cell and nerve development.

"What this means is, for the remainder of that child's life, irrevocably the child will learn less in school, will earn less later, is more vulnerable to disease," he said. "This is a tragic violation of that child's life, but it's also a tremendous strain on that society."

The U.N. report found that 24 countries with the highest levels of stunted children were concentrated in sub-Saharan Africa and South Asia. More than half of those under age 5 in Timor-Leste, Burundi, Niger and Madagascar suffered from stunting. The country with the largest number of stunted children was India with 61.7 million, or 48 percent of all Indians under age 5.

Lake said the problem of stunted child development was growing in Syria because of its civil war and widespread disruption to medical care, schools and family life. Even before the onset of war, the report found, Syria's stunting rate for its children was 28 percent.

When asked what part of the world most needed attention, Lake said he could offer only "a sad litany of how many spots there are."

But he said in every country where stunting was identified as a major problem, UNICEF officials were working with local aid agencies and the government. He said even Syria and North Korea permitted U.N. and local officials to distribute the water, vitamins and education to expectant mothers.

"I've never had any (country) push back," he said. "There's a natural reluctance among all governments to say: 'Yes we have a problem that we could have fixed quicker.' So you're always going to get a little bit of denial. But I've never heard of a country that said: 'No, we're not going to deal with it.'"

Lake noted that ensuring ideal growth during the key first 2 years of life didn't just mean eating a lot.

"People too often assume if you get enough food to eat, you're getting enough nutrition to head off malnutrition or stunting. The fact is you can eat lots of food and not get enough nutrients," he said, noting that India suffered no food shortages yet produced 38 percent of the world's stunted children.

He said women in the Third World particularly needed to focus on breast feeding for the child's first six months because exposing the child to local tainted water supplies could mean diarrhea, one of the greatest killers in poor countries. Lake said diarrhea, if it didn't kill the child, "washes the nutrients out of the kid and stunts them."