The World Health Organization (WHO) said it had been compelled to cancel a mission to bring medical supplies to northern Gaza on Sunday after failing to receive security guarantees.

It was the fourth time WHO had had to call off a planned mission to bring urgently needed medical supplies to Al-Awda Hospital and the central drug store in northern Gaza since Dec. 26, it said.

"It has now been 12 days since we were last able to reach northern Gaza," the WHO office in the occupied Palestinian territories wrote on the X social media platform.

"Heavy bombardment, movement restrictions, and interrupted communications are making it nearly impossible to deliver medical supplies regularly and safely across Gaza, particularly in the north."

The delivery planned on Sunday, WHO said, had been designed to sustain the operations of five hospitals in the northern part of the enclave.

Israeli government spokesperson Eylon Levy said he did not have information on WHO's assertion, referring questions to the Israel Defence Forces.

WHO Director-General Tedros Adhanom Ghebreyesus said he was "shocked by the scale of health needs and devastation in northern Gaza".

"Further delays will lead to more death and suffering for far too many people," he wrote on X.

In separate comments, the International Rescue Committee aid group said its emergency medical team and the Medical Aid for Palestinians charity had been forced to withdraw and cease its activities at the Al-Aqsa Hospital in Gaza's Middle Area due to increasing Israel military activity in the area.

The Israeli offensive launched in the wake of a deadly rampage by Hamas in southern Israel on Oct. 7 has displaced most of Gaza's 2.3 million population, left many homes and civilian infrastructure in ruins, and caused acute shortages of food, water and medicine.