SANAA - Almost 21 million people in war-torn Yemen, or nearly 70 percent of the total population, need life-saving humanitarian assistance, the United Nations Children's Fund said in a Twitter post on Monday.

"This includes 11.3 million children or nearly 80 percent of children," the UNICEF noted.

In Yemen, nearly 400,000 children under the age of five are slipping from acute malnutrition to severe acute malnutrition, the humanitarian agency said.

Yemen has been mired in a civil war since late 2014 when the Iran-backed Houthi militia seized control of several northern provinces and forced the Saudi-backed Yemeni government of President Abd-Rabbu Mansour Hadi out of the capital Sanaa.

The United Nations is trying to end the seven-year-old civil war that has killed tens of thousands of people, displaced 4 million, and brought the country to the brink of famine.