More than 200 million children worldwide under age 5 do not get basic health care, leading to nearly 10 million deaths annually from treatable ailments like diarrhea and pneumonia, according to a U.S.-based charity.

Nearly all of the deaths occur in the developing world, with poor children facing twice the risk of dying compared to richer children, according to Save the Children's global report.

Sweden, Norway and Iceland top the ranking in terms of well-being for mothers and children in 146 countries surveyed, while Nigeria ranks last.

Eight out of 10 bottom-ranked countries are in sub-Saharan Africa, where four out of five mothers are likely to lose a child in their lifetime, Save the Children said.

The top three among the 55 developing countries ranked in the survey are the Philippines, Peru and South Africa - all surveyed for the first time. Indonesia and Turkmenistan tied for fourth.

Laos, Yemen, Chad, Somalia and Ethiopia were found doing the worst among developing countries, the report said.

Through a number of health initiatives, including access to oral rehydration to treat diarrhea, the Philippines has nearly cut its child death rate in half since 1990, said David Oot, Save the Children's associate vice president.

Today, more than 75 percent of Filipino children with diarrhea receive rehydration therapy, compared with 15 percent of Ethiopian children, he said.

An alarming number of countries are failing to provide the most basic health services that would save lives, with 30 percent of children in developing countries not getting basic health intervention such as prenatal care, skilled assistance during birth, immunizations and treatment for diarrhea and pneumonia.

Wide disparities in health care for the poorest and best-off children are seen even in the highest-ranked countries, the report said.

In the Philippines and Peru, for example, the poorest children are 3.2 times more likely to go without essential health care than their best-off counterparts.

The poorest Peruvian children are 7.4 times more likely to die than their richest counterparts, while the chances are 3.2 times higher for poor Filipino children.

In Latin America, Brazil, Bolivia and Peru have some of the world's widest survival gaps between rich and poor children. In Asia, large disparities also exist in India and Indonesia.

Use of existing, low-cost tools and knowledge could save more than 6 million of the 9.7 million children who die yearly from easily preventable or curable causes, the report said.

They include antibiotics that cost less than $0.30 to treat pneumonia, the top killer of children under 5, and oral rehydration therapy - a simple solution of salt, sugar and potassium - for diarrhea, the second top killer.