The new figures, which were taken from surveys of some 139 countries and a re-analysis of existing data, are lower than previous estimates attributing 50 percent of childhood deaths to undernutrition -- a severe form of malnutrition, the international team of researchers said.

The researchers estimated that problems relating to a severe lack of food resulted in 2.2 million deaths of children under the age of five in 2005.

Too many children still die needlessly due to a lack of coordination among governments, private donor groups and non-governmental organizations, they wrote in a special series of reports in the journal Lancet.

"This latest Lancet series concludes, not surprisingly perhaps, that the international nutrition system is broken," Richard Horton, the journal's editor, wrote in a commentary. "Leadership is absent, resources are too few, capacity is fragile and emergency responses systems are urgently needed."

Undernourished children who survive face a lifetime of poor health and developmental problems that will hinder them both socially and economically as they grow older, the researchers said.

"We conclude that damage suffered in early life leads to permanent impairment, and might also affect future generations," said Caroline Fall, an epidemiologist at the University of Southampton in Britain, who worked on one of the studies.

"Populations who have been affected by this are not going to be able to climb out of poverty."

Other researchers said early intervention was key. Things like promoting breastfeeding and providing Vitamin A supplements were examples of programmes that, if made available early, could prevent 25 percent of all child deaths in the 36 countries with the biggest problem with undernutrition, they said.

Four regions -- Africa, Asia, western Pacific and the Middle East -- contain four-fifths of undernourished children and focusing on these areas would go a long way toward meeting global targets to sharply reduce poverty by 2015, they added.

Medecins Sans Frontieres welcomed the papers for putting a spotlight on the often neglected issue of childhood undernutrition but criticized the findings for underestimating child deaths and failing to endorse home-based care.

"Because of weaknesses in analysis and outmoded recommendations, the series is undermining efforts to promote urgently needed change," the group said in a statement.