The United Nations humanitarian office says Israeli authorities are systematically denying it access to northern Gaza to deliver aid and this had significantly hindered the humanitarian operation there.
"The operations in the north have become increasingly more complicated," said Andrea De Domenico, head of office for the UN Office for the Coordination of Humanitarian Affairs (OCHA) in the Occupied Palestinian Territories.
"We have systematic refusal from the Israeli side of our effort to get there, to access the north."
Israeli authorities and COGAT - an Israeli Defence Ministry agency tasked with coordinating aid deliveries into Palestinian territories - did not immediately respond to requests for comment.
Israel has previously denied blocking the entry of aid.
The Israeli offensive launched in the wake of a deadly rampage by Hamas militants in southern Israel on October 7 has displaced most of Gaza's 2.3 million population, destroyed civilian infrastructure, and caused acute shortages of food, water and medicine.
Since the start of hostilities, aid deliveries to northern Gaza have been limited, and the area was cut off altogether from external aid for weeks earlier in the conflict.
De Domenico said Israel was concerned about fuel deliveries and other supplies that could be diverted to Hamas, and had been reluctant to authorise aid deliveries to hospitals in north Gaza.
"In particular, they have been very systematic in not allowing us to support hospitals, which is something that is reaching a level of inhumanity that, for me, is beyond comprehension," he said.
De Domenico said OCHA had not been authorised to return to Jabalia, and was allowed to bring only a very precise quantity of fuel to Al-Shifa Hospital that would last for a determined period.
In separate comments, the UN human rights office said that Israel, facing genocide accusations at the top UN court in The Hague this week, had repeatedly failed to uphold international humanitarian law.
"We've repeatedly highlighted Israel's recurring failures to uphold the fundamental principles of international humanitarian law: distinction, proportionality and precautions in carrying out attacks," said Elizabeth Throssell , spokesperson for the Office of the UN High Commissioner for Human Rights (OHCHR).
"The High Commissioner has stressed that breaches of these obligations risk exposure to liability for war crimes, and has also warned of the risks of other atrocity crimes."
Israel has denied allegations that it has committed war crimes.
