The number of children under the age of five who die annually fell to less than 7 million in 2011, but around 19,000 boys and girls around the world are still dying every day from largely preventable causes, the U.N. children's agency said in a report released Wednesday night.

The report by the United Nations Children's Fund said that four-fifths of under-five deaths last year occurred in sub-Saharan Africa and South Asia. More than half the pneumonia and diarrhea deaths - which together account for almost 30 percent of under-five deaths worldwide - occur in just four countries: Congo, India, Nigeria and Pakistan, it said.

"Given the prospect that these regions, especially sub-Saharan Africa, will account for the bulk of the world's births in the next years, we must give new impetus to the global momentum to reduce under-five deaths," UNICEF Executive Director Anthony Lake said in the report.

He said youngsters from disadvantaged and marginalized families in poor and fragile nations are the most likely to die before their fifth birthday, but their lives can be saved with vaccines, adequate nutrition and basic medical and maternal care.

"The world has the technology and know-how to do so," Lake said. "The challenge is to make these available to every child."

UNICEF said the rate of decline in under-five deaths has drastically accelerated in the last decade, from 1.8 percent per year during the 1990s to 3.2 percent per year between 2000 and 2011.

"There is much to celebrate," Lake said. "More children now survive their fifth birthday than ever before - the global number of under-five deaths has fallen from around 12 million in 1990 to an estimated 6.9 million in 2011."

In 2010, there were 7.6 million under-5 deaths.

The report underscores that a country's location and economic status need not be a barrier to reducing child deaths.

Low income countries such as Bangladesh, Liberia and Rwanda, middle income countries including Brazil, Mongolia and Turkey, and high income countries such as Oman and Portugal have all made dramatic gains, lowering their under-five mortality rates by more than two-thirds between 1990 and 2011, the report said.

But UNICEF Deputy Executive Director Geeta Rao Gupta stressed that there is "unfinished business" and it is not just about the number of child deaths.

"Behind every statistic is an unseen child, and a grieving mother and father," she said. "A child's death is all the more tragic when caused by a disease that can easily be prevented. That's why we have this global movement to recommit to child survival and renew the promise to end child deaths. This decline shows we can make this happen."