Eighty percent of Yemen’s population, or more than 20 million people, need some form of humanitarian assistance as Arab air strikes and civil war ravage the impoverished country, aid agency UNICEF said on Thursday.

Eighty percent of Yemen's population, or more than 20 million people, need some form of humanitarian assistance as Arab air strikes and civil war ravage the impoverished country, aid agency UNICEF said on Thursday.

The figure is up by almost 5 million people since the organization's latest report last week.

For over 11 weeks, a Saudi-led coalition has been bombing Yemen in a bid to restore power to fugitive president Abd Rabbuh Mansour Hadi who is a close ally to Riyadh.

The alliance's de facto blockade of Yemen's air space and ports has cut off supplies of food and fuel to the parched country, where gas-powered pumps providing water for drinking and sanitation now lie mostly inoperable.

"20.4 million people are now estimated to be in need of some form of humanitarian assistance, of whom 9.3 million are children," Jeremy Hopkins, Deputy Representative of UNICEF, said from the capital, Sana’a.

"The de facto blockade on Yemen's ports, though there is some easing, means fuel is not coming into the country, and since pumps are mechanized that means over 20 million people don't have access to safe water," he added.

Other urgent humanitarian needs, he said, include malnutrition, shortages of medical supplies, mounting civilian casualties in airstrikes, recruitment of child soldiers and damage to schools by the warring sides.

Even before the conflict, UNICEF said around 10 million people in Yemen needed humanitarian assistance, a product of decades of underdevelopment in the mountainous and barely governed Arabian Peninsula state.