The Indian prime minister has called local levels of child malnutrition in the country a "national shame" and pledged stronger action to bring hundreds of millions of his people out of poverty.
The levels were almost twice as high those found in sub-Saharan Africa, said the report, which is based on data collected by over 1,000 surveyors who interviewed 74,020 mothers and measured 109,093 children.
Campaigners have long raised the issue of child malnutrition as a measure of how many Indians still live in deep poverty. However, the researchers also found that rates of child malnutrition are significant among wealthier families.
The number of underweight children in India has dropped by a fifth over seven years. Though "encouraging" this was still "unacceptably high", said Singh, who leads a beleaguered coalition government.
Public distribution schemes designed to combat child malnutrition in India are among the biggest in the world. However, endemic graft and logistic problems mean that only a fraction of the aid actually reaches the needy.
The Indian government now hopes to put a new subsidy scheme in place. Critics have attacked the programme as unworkable and expensive. Continuing food inflation is also causing problems for many of India's worst-off.
In 2010 researchers at Oxford University found that there were more poor people in eight states of India than in the 26 countries of sub-Saharan Africa. More than 410 million people live in poverty in the eight states where the "intensity" of the poverty in parts of India is equal to, if not worse than, that in the Democratic Republic of the Congo, the war-racked African nation.
The new report identified a lack of basic hygiene in India as one serious problem, finding that only 11% of mothers said they used soap to wash hands before a meal and only 19% after a visit to the toilet.