At least 10 million children under age five die annually from treatable ailments, mostly in developing countries, because they lack basic health care needs, a U.S.-based non-profit organization said Wednesday.

According to Save the Children, poor children face the risk of dying at a younger age compared to children in wealthier countries.

A study by the organization said that Nigeria ranks the least out of 146 countries surveyed in terms of healthy mothers and children.

Sweden, Iceland and Norway top the ranking of healthy mothers and children in the survey.

The report found that in sub-Saharan Africa where famine, conflict and diseases such as AIDS were rampant, infant and child mortality was higher.

A 2005 World Development Indicators report by the World Bank found that 48 percent of child death occurred in developing countries.