The head of the World Health Organisation said on Wednesday it had lost touch with health personnel at Al Shifa Hospital in Gaza after Israeli forces began raiding the facility.

WHO director-general Tedros Adhanom Ghebreyesus said the reports of the military incursion into Shifa were deeply concerning.

“We’ve lost touch again with health personnel at the hospital. We’re extremely worried for their and their patients’ safety,” he said on social media platform X.

In separate comments, UN aid chief Martin Griffiths said on Wednesday he was “appalled” by reports of the raids.

“The protection of newborns, patients, medical staff and all civilians must override all other concerns,” he wrote on X.

“Hospitals are not battlegrounds.”

Israeli troops entered Shifa, Gaza’s biggest hospital, on Wednesday and were searching its rooms and basement, witnesses said. Israel says Hamas fighters have a headquarters in tunnels beneath it. Hamas denies this is the case.

The WHO, a UN agency, also said it was “urgently exploring” the possibility for evacuating patients and medical staff from the facility.

“To make sure this can be enabled, of course there is a need for safe passage and also for fuel for the ambulances,” said Rik Peeperkorn, WHO representative in the occupied Palestinian territories.

Peeperkorn said that according to their latest information, 34 of 39 premature infants in the hospital were still alive, and 82 bodies had been buried in a mass grave in the grounds.

A further 80 bodies remained unburied, he said, and there was no oxygen, power or water at the hospital. There are 633 patients there in total, plus around 500 staff and up to 4,000 people sheltering in the hospital grounds, he added.