GENEVA (Reuters) – Mothers and newborn babies in Gaza face dire conditions as Nasser hospital in the south of the enclave is overwhelmed with patients fleeing the north and medical resources running out, UNICEF said on Friday.

“The situation for mothers and newborns in Gaza has never been worse. In Nasser hospital, we’re seeing hospital corridors lined with women who’ve just given birth,” UNICEF spokesperson James Elder told reporters in Geneva via video link from Gaza.

The World Health Organization said on Friday that the health system was on the brink of collapse.

Dr. Rik Peeperkorn, WHO’s representative for the occupied Palestinian Territory said he had never seen Nasser hospital so crowded, as patients flee from Gaza City—which is at the center of Israel’s expanded military offensive, towards the south of the enclave.

Israel has told the entire million-strong population of Gaza City to head south as it mounts one of the biggest offensives of the war this month, vowing to root out Hamas fighters in what it says are their last bastions in Gaza’s biggest urban area.

“Every corridor you see mattresses and patients on the floor. There’s a huge increase,” Dr. Peeperkorn said, adding that a large number of patients are coming from the north.

Only 14 of Gaza’s 36 hospitals remained partly functional, according to the WHO.

Mr. Elder described new mothers and their newborn children lying on the floor in Nasser hospital, and also reported seeing three premature babies sharing a single oxygen source.

“They shared 20 minutes each. The other two children cry while the third child gets that oxygen for 20 minutes,” Mr. Elder said.

The WHO says there is a vast shortage of medical supplies.

“We see fast declining shortages of essential items such as dressing kits, gauzes...but also everything relates to blood supplies and transfusion kits,” Dr. Peeperkorn said, reporting ongoing problems getting the supplies in.

Israel says there is no quantitative limit on aid entering Gaza and accuses Hamas, which it has been at war with for nearly two years, of stealing aid—accusations the Palestinian militant group denies.