UNITED NATIONS -- UN Secretary-General on Tuesday stated that the amount of aid permitted into the Gaza Strip is "completely inadequate" to address the growing needs of the civilians caught in the escalating fighting.

The top UN official further emphasized his plea for an "immediate humanitarian ceasefire" between Israeli forces and Hamas, the group in control of the Gaza Strip, as well other militant groups.

In a statement, Guterres said depriving Gaza's people basic supplies was only "compounding the human tragedy" of the conflict, calling for unimpeded humanitarian access "to be granted consistently, safely and to scale in order to meet the urgent needs created by the catastrophe unfolding in Gaza."

He said he was deeply alarmed by the intensifying violence, including the expansion of ground operations by the Israel Defense Forces accompanied by further intense air strikes, and the continued rocket fire toward Israel from Gaza.

"Civilians have borne the brunt of the current fighting from the outset. Protection of civilians on both sides is paramount and must be respected at all times," he said.

The Hamas-run Ministry of Health reported that over 8,300 people had been killed in Gaza since Oct 7, including 3,547 children, 2,136 women and 480 elderly persons.

The latest figures released by the UN Palestine refugee agency, UNRWA, which has around 13,000 staff working in Gaza, put the extent of the humanitarian crisis into stark relief.

The agency said 670,000 internally displaced people are sheltering in 150 UNRWA installations.

"The situation in shelters remains critical with very limited assistance available and no additional space," said the agency, with healthcare dwindling and protection risks rising.

Furthermore, UNRWA itself lost a further three staff members in the ongoing airstrikes during the past 24 hours - killed in their houses along with their families, according to agency. This brings the death toll to 67.

"I mourn and honor the United Nations colleagues who have tragically been killed in the bombardment of Gaza over the past three weeks," said the UN chief. "My heart goes out to the families of our colleagues who lost their lives in service."

Guterres repeated his "utter condemnation of the acts of terror perpetrated by Hamas" on Oct 7.

"There is never any justification for the killing, injuring and abduction of civilians. I appeal for the immediate and unconditional release of those civilians held hostage by Hamas," he said.

Guterres stressed again that international humanitarian law "establishes clear rules that cannot be ignored. It is not an a la carte menu and cannot be applied selectively."

All parties must abide by the rules, "including the principles of distinction, proportionality, and precaution."

Regarding the potential risks of conflicts spreading across borders into Lebanon and Syria, the UN chief said he was "deeply concerned about the risk of a dangerous escalation," calling on all regional leaders to exercise utmost restraint.