By Beh Lih Yi

KUALA LUMPUR (Thomson Reuters Foundation) - Sixty percent of the world's 5.9 million children who died before their fifth birthday last year were in 10 countries in Asia and Africa, said a study published on Friday, prompting calls for action to reduce the mortality.

The study published in The Lancet medical journal said the latest data highlights the inequality in children's death among the 194 countries it studied, even though the number of under-five deaths has fallen by 4 million compared to 2010.

Of the 5.9 million deaths last year, 3.6 million happened in 10 Asian and African countries - India, Nigeria, Pakistan, the Democratic Republic of Congo, Ethiopia, China, Angola, Indonesia, Bangladesh and Tanzania.

The two leading causes were complications due to premature birth and pneumonia, according to researchers from the Johns Hopkins Bloomberg School of Public Health, the London School of Hygiene and Tropical Medicine and the World Health Organization.

The researchers said child survival has improved substantially, although countries failed to meet the U.N. Millennium Development Goal to cut the rate of under-five deaths by two-thirds between 1990 and 2015.

The rate fell by 53 percent over the period.

The slow progress to reduce newborn deaths - in the first 28 days of life - hampered the MDG target, the researchers said. Of the 5.9 million under-five deaths in 2015, 2.7 million were newborns.

"The problem is that this progress is uneven across all countries, meaning a high child death rate persists in many countries," said the study's lead author Li Liu, from the Johns Hopkins Bloomberg School of Public Health in the U.S.

"Substantial progress is needed for countries in sub-Saharan Africa and Southern Asia to achieve the child survival target of the Sustainable Development Goals," she added.

Under the Sustainable Development Goals, which replaced the MDGs last year, all countries aim to reduce under-five mortality to no more than 25 deaths per 1,000 births by 2030.

The researchers recommended breastfeeding, vaccines for pneumonia, malaria and diarrhea, as well as improving water and sanitation to help with children's survival.

(Reporting by Beh Lih Yi @behlihyi, editing by Alisa Tang)