The UN urgently needs $350m for hungry children in war-torn Yemen - a figure that is "peanuts" compared with what is being spent on deadly weapons in the conflict.

The comments by Geert Cappelaere, Middle East and North Africa director at the UN children's fund UNICEF, on Sunday, appeared to mock US President Donald Trump, who last week described billions of dollars in Saudi arms purchases as "peanuts".

"UNICEF is asking for 2018 alone for its humanitarian programme close to $350m. That is peanuts compared to the billions of dollars that are currently invested in fighting war. We are asking for peanuts," Cappelaere told reporters in Amman, Jordan.

Trump hosted Crown Prince Mohammed bin Salman at the White House last Tuesday and said Saudi Arabia would be spending "peanuts" by purchasing $12.5bn worth of military hardware from the United States.

Saudi Arabia leads a military coalition in Yemen fighting Houthi rebels.

According to the United Nations, the ongoing war has killed more than 10,000 people and wounded more than 40,000. The UN describes Yemen as the "worst humanitarian crisis in the world".

About 8.4 million Yemenis face imminent famine as the country also battles cholera and diphtheria outbreaks.

'Slightest respect'

Cappelaere said the "brutal senseless war on children to stop now".

"Five children were killed every single day in Yemen in 2017," he said, while "every single girl or boy in Yemen is facing acute humanitarian needs".

An estimated 80 percent of all Yemenis are living in poverty, Cappelaere said.

He also expressed fears of a total collapse of the education and health systems in the country. As Yemen's devastating civil war enters its fourth year, about 2,500 schools are no longer operating, according to UNICEF.

The Houthi rebels overthrew Yemen's internationally recognised government and in response, the Saudi-led coalition launched a deadly air campaign in March 2015 after fighters seized the capital, Sanaa.

"None of the parties - or those who have influence over the fighting parties - have for a single second ... shown the slightest respect for the protection of children," said Cappelaere.