The WHO said 85 patients had been evacuated Tuesday from Gaza to the United Arab Emirates, in the largest medical evacuation from the Palestinian territory since the war began in October.
The World Health Organization said the sick and severely injured patients evacuated to the Gulf country comprised 35 children and 50 adults, who were accompanied by 63 family members and caregivers.
The UN's health agency confirmed to AFP it was the largest number of patients that have been transferred from the Gaza Strip in a single operation since the war began.
They were transferred from Gaza via the Kerem Shalom crossing into Israel, and then to Ramon Airport near Eilat in southern Israel, from where they were flown to Abu Dhabi.
"Fifty-three patients have cancer, including four children; 20 have trauma injuries; three have blood diseases, including thalassemia; three have congenital conditions; two have fanconi anaemia; one has a neurological condition; one has cardiac disease; one has liver disease; and one has renal failure," the WHO said.
The patients were collected from several locations and field hospitals across Gaza.
The evacuation was postponed from Monday and took place under "extremely challenging conditions" amid insecurity and damaged roads, the WHO said.
The agency provided wheelchairs to ensure patients could switch buses safely at Kerem Shalom, and medical professionals went with the patients within Gaza and en route to the airport.
"We are thankful to the UAE for supporting the evacuation of these patients to receive the urgent care they need," said WHO chief Tedros Adhanom Ghebreyesus.
"We hope this paves the way for the establishment of evacuation corridors via all possible routes, including the Kerem Shalom and Rafah crossings to Egypt and Jordan, and from there to other countries.
"We also call for evacuations to the West Bank, including East Jerusalem, to be restored. Thousands of sick people are suffering needlessly. Above all, and as always, we call for a ceasefire."
Since October, around 5,000 people have been evacuated for treatment outside Gaza, with more than 80 percent of those receiving care in Egypt, Qatar and the UAE.
However, more than 10,000 others in Gaza still need medical evacuation, the WHO said.
The WHO's Eastern Mediterranean regional director Hanan Balkhy called on more countries in the Middle East to give Gazan evacuees lifesaving care.
"Support to people in the region must start from the region," she said.
