Newborn mortality is rising sharply in the Gaza Strip, with babies being born underweight, the World Health Organization said Tuesday, citing medics on the ground.

"From different doctors, particularly in the maternity hospitals, they're reporting that they're seeing a big rise in children born with low birth weight, and just not surviving the neonatal period because they're born too small," WHO spokeswoman Margaret Harris said at a briefing in Geneva.

She said that at Kamal Adwan, the only paediatric hospital in northern Gaza, "at least 15 malnourished children are coming in per day, and the needs are just getting ever more severe".

The WHO is unable to establish precise statistics on child mortality because of the devastation in the Palestinian territory after six months of war between Israel and Hamas, with Harris saying many people do not even get to hospital.

She cited a stabilisation centre set up last week, saying the inpatients were typically children with medical illnesses as well as malnutrition.

"If you have got an underlying condition, malnutrition will kill you much more quickly, so they become the most urgent patients," she said.

On Monday, the Israeli army pulled out of Gaza City's Al-Shifa Hospital after a two-week military operation that left much of the complex in ruins and bodies scattered on the dusty grounds.

The hospital was the biggest in the Palestinian territory.

"Al-Shifa Medical Complex is gone forever," its acting director Marwaan Abu Saadah said in a WHO video filmed at the scene.

Harris added: "It's no longer able to function in any shape or form as a hospital."

"Destroying Al-Shifa means ripping the heart out of the health system," she said, noting that it was a major hospital with 750 beds, 25 operating theatres, and 30 intensive care wards.

Israel said it had battled Palestinian militants inside the complex, killing at least 200 and recovering stockpiles of weapons, explosives, and cash.

The bloodiest-ever Gaza war erupted with Hamas's October 7 attack, which resulted in about 1,160 deaths in Israel, mostly civilians, according to an AFP tally based on Israeli official figures.

Israel's retaliatory campaign has killed at least 32,916 people, mostly women and children, according to the health ministry in Hamas-run Gaza.