GENEVA (Reuters) - Hundreds of thousands of children in Yemen face life-threatening malnutrition, millions lack access to health care or clean water, and some have been drafted as soldiers in the year-old war, the United Nations Children’s Fund said on Tuesday.

A boy walks past the a house damaged by a Saudi-led air strike in Yemen's capital Sanaa, September 12, 2015. REUTERS/Mohamed al-Sayaghi

A UNICEF report said all sides had “exponentially increased” the use of child soldiers in the conflict between Houthi forces, allied to Iran, and a Saudi-led coalition supporting Yemen’s President Abd-Rabbu Mansour Hadi. It knew of 848 documented cases, including boys as young as 10.

“On average, at least six children have been killed or injured every day,” said the report “Childhood on the Brink”. UNICEF has confirmed 934 children directly killed and 1,356 injured, but says they are “only a tip of the iceberg”.

“Sixty-one percent of those (children) killed and injured were in (Saudi-led) air strikes across the country,” Julien Harneis, UNICEF’s Representative in Yemen, told a briefing by telephone from the capital Sanaa.

All sides have violated international law by using indiscriminate and disproportionate force that means “children die unnecessarily and wrongly”, he said, citing multiple coalition strikes on outdoor markets.

Basic services and infrastructure are “on the verge of total collapse,” the report said, noting attacks on schools, hospitals and the water and sanitation system.

The U.N. said last week the warring parties had agreed to a cessation of hostilities from April 10 and peace talks from April 18, after a year of war that has killed more than 6,200 people.

“We’re hoping that the truce kicks in on the 10th and will allow parents and families to come and access health services and other services,” Harneis told Reuters earlier.

“In Sa’ada in the last week, there has definitely been a reduction of fighting in the border area. In Sanaa, we have seen fewer (Saudi-led) air strikes,” he said.

Nearly half of Yemen’s 22 provinces are on the verge of famine, the U.N.’s World Food Programme said last week.

UNICEF delivers nutritional supplies and vaccines against measles, polio and other childhood diseases in the country of 24 million, but it is not enough, Harneis said.

“We’ve got an increase in both severe acute malnutrition and chronic malnutrition,” he said.

The report said an estimated 320,000 children risk severe acute malnutrition, which can leave a child vulnerable to deadly respiratory infections, pneumonia and water-borne diseases. For now UNICEF is only able to reach 200,000 of them, Harneis said.

Nearly 10 million children require humanitarian aid to prevent a further deterioration. Chronic malnutrition can stunt growth and development.

“UNICEF estimates that nearly 10,000 children under 5 years may have died in the past year from preventable diseases,” it said, citing lower vaccination rates and declines in treatment.