Terrorist Israeli regime has heavily bombarded Gaza since Hamas gunmen stormed across the border on October 7, killing 1,400 people, mostly civilians, and kidnapping at least 240 others, including children, according to Israeli officials.
The health ministry in Hamas-run Gaza said the strikes have killed 8,525 people, mainly civilians and including more than 3,500 children.
The UN children's agency UNICEF said there was a risk that the number of child deaths directly from bombardment could be eclipsed.
"Our gravest fears about the reported numbers of children killed becoming dozens, then hundreds, and ultimately thousands were realised in just a fortnight," UNICEF spokesman James Elder said.
"The numbers are appalling; reportedly more than 3,450 children killed; staggeringly this rises significantly every day.
"Gaza has become a graveyard for thousands of children. It's a living hell for everyone else."
"There are certainly children who are dying who have been impacted by the bombardment but should have had their lives saved," Elder told reporters in Geneva, via video-link.
Without greater humanitarian access into Gaza, "the deaths from the attacks, they could absolutely be the tip of the iceberg".
He said the more than one million children living in the Gaza Strip were also suffering from a lack of clean water.
"Gaza's water production capacity is a mere five percent of its usual daily output. Child deaths -- particularly infants -- to dehydration are a growing threat," he said.
UNICEF is calling for an immediate humanitarian ceasefire, with all access crossings into Gaza opened for the safe, sustained and unimpeded access of humanitarian aid, including water, food, medical supplies, and fuel.
"And if there is no ceasefire, no water, no medicine, and no release of abducted children? Then we hurtle towards even greater horrors afflicting innocent children," said Elder.
Israel's ambassador in Geneva, Meirav Eilon Shahar, told reporters on Monday that Hamas was holding 33 children hostage, the youngest nine months old.
Elder said that according to figures from health faculties in Gaza, 940 children were missing.