Nearly 1.5 million people are currently displaced in a country of about 11 million, and more than five million are facing severe food insecurity, according to UN figures.
The UN system will convene more than 30 side events during the summit, covering areas such as agriculture and food security, gender equality, and health systems.
In the Gaza Strip, the war-shattered Palestinian territory is gripped by dire humanitarian conditions created by 21 months of war and made worse by Israel's total blockade of aid from March to May.
Guterres denounced the killing of civilians, especially children, in Gaza as Israel wages a relentless air and ground campaign in retaliation for the October 7 attacks by Hamas.
He appealed for an "immediate humanitarian ceasefire" in the war between Israel and Hamas in Gaza, reiterating what he called "two urgent humanitarian appeals".
