New York, New York - The heads of all major UN agencies issued a rare joint statement Sunday expressing outrage at the civilian death toll in Gaza and calling for an "immediate humanitarian ceasefire" in Israel's month-long assault on the territory.

"For almost a month, the world has been watching the unfolding situation in Israel and the Occupied Palestinian Territory in shock and horror at the spiraling numbers of lives lost and torn apart," the UN chiefs said.

The heads of 18 organizations including UNICEF, the World Food Program, and the World Health Organization described the horrific toll on both sides since the October 7 Hamas cross-border attack from Gaza into Israel, which left about 1,400 people dead, mainly civilians, according to Israeli authorities.

Israel has retaliated with relentless air and artillery strikes that have killed at least 9,770 people, as many as 4,000 of which are children, per Gaza's health authorities – which has consistently produced reliable data.

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The UN statement said "an entire population is besieged and under attack, denied access to the essentials for survival, bombed in their homes, shelters, hospitals and places of worship. This is unacceptable."

It called on Hamas to release the more than 240 hostages it took in its attack, and urged both sides to respect their obligations under international law as the war rages on.

The UN leaders said more food, water, medicine and fuel must be allowed into Gaza to help its besieged population.

"We need an immediate humanitarian ceasefire. It’s been 30 days. Enough is enough. This must stop now," the statement said.

Despite the call, Israel on Monday violently pounded Gaza with strikes, including obliterating the al-Maghazi refugee camp in the center of the strip, where civilians had been told to seek shelter.