Six children have been killed or maimed daily in Yemen since Saudi-led air strikes began a year ago, the UN said Tuesday, warning the conflict was taking a horrifying toll on the country's youth.

In a report marking the anniversary of the start of the Saudi-led campaign, the UN children's agency said nearly a third of the more than 3,000 civilians killed in Yemen were children.

"Children are not safe anywhere in Yemen. Even playing or sleeping has become dangerous," UNICEF representative in Yemen Julien Harneis told AFP in an email.

The Saudi-led intervention in support of President Abedrabbo Mansour Hadi began on March 26 last year, but has yet to deal a decisive blow to the Huthi rebels and their allies, who still control Sanaa and key parts of the country.

Hopes for a breakthrough in the conflict emerged last week when the warring sides agreed on a ceasefire to be observed before peace talks on April 18.

A halt to the violence is sorely needed in what before the escalation of the conflict was already one of the world's poorest nations.

The UN estimates 82 percent of the population is now in desperate need of humanitarian aid, with 320,000 children considered severely malnourished.

"The scale of suffering in the country is staggering," Tuesday's report said, providing heart-wrenching testimony from children caught up in the  violence.

"Everything around me is frightening. My mother's sad face and tears are what torture me the most," said 13-year-old Abdullah Nawar, who is trapped with his family in Aden.

"I am scared that all of us will die in this dark basement," he added.

 'Extreme and cruel'

 In addition to the thousands of children who have been direct victims of the violence and "hurt in the most extreme and cruel ways", Tuesday's report showed even more were suffering the secondary effects of the fighting.

"Basic services and infrastructure in Yemen are on the verge of total collapse," it said.

UNICEF estimates that close to 10,000 children under five may have died over the past year alone from preventable diseases as a result of the decline in access to vaccines and other key health services.

This comes on top of the nearly 50,000 children who die every year in Yemen before their fifth birthday, the agency said. 

The UN says 63 healthcare facilities have been attacked over the past year and three have been occupied for military purposes.

Children, desperate for a sense of normalcy amid the physical and emotional violence they are experiencing, are also often cut off from attending school, which provides a compass point.

There had been more than 50 direct attacks on schools and teachers, and some 50 schools have been occupied by fighters, UNICEF said.

More than 1,600 schools meanwhile remain closed due to insecurity, infrastructure damage or because they are being used to house some of the some 2.4 million people who have been displaced by the conflict.

Many children are also being forced to take part in the violence surrounding them.

UNICEF said it had documented 848 cases of children being recruited by different sides in the conflict, with reports indicating children as young as 10 were forced to take part in the fighting.

"Tragic as it is, these statistics are only a tip of the iceberg," the report said, adding that the actual numbers were likely "much higher".