The United Nations has issued a report warning that the number of death toll in Saudi-led war on Yemen is expected to reach 377,000 by the end of the year 2021.

In a report published on Tuesday, the United Nations Development Programme (UNDP) estimated that 70 percent of those killed would be children under the age of five, Al-Jazeera reported. 

It found that 60 percent of deaths would have been the result of indirect causes, such as hunger and preventable diseases, with the remainder a result of direct causes like front-line combat and air raids.

“In the case of Yemen, we believe that the number of people who have actually died as a consequence of conflict exceeds the number who died on the battlefield,” UNDP Administrator Achim Steiner said.

Since March 2015, Saudi Arabia and some of its Arab allies have been carrying out deadly airstrikes against the Houthi Ansarullah movement in an attempt to restore power to fugitive former president Abd Rabbouh Mansour Hadi, a close ally of Riyadh.

The war has killed tens of thousands of people, mostly civilians, and resulted in what the UN has described as the world's worst humanitarian crisis.

The children are among tens of thousands of Yemenis, who have died since March 2015, when the kingdom and its allies began taking the Arab world’s poorest nation under a wholesale war.

The fatalities have, in part, been caused by the coalition’s application of Western-provided precision ammunition on crowded civilian centers and residential areas.