Tedros Adhanom Ghebreyesus told a press conference that health workers need freedom of movement in Gaza to administer the vaccines, saying that a ceasefire or at least a few days of calm, was essential to protect Gaza's children.

"WHO is sending more than 1 million polio vaccines which will be administered in the coming weeks," he said.

On July 30, the health ministry in Gaza declared the Palestinian territory to be a "polio epidemic zone", blaming the reappearance of the virus on Israel's military offensive since October 7 and the resulting destruction of health facilities.

The ministry said the CPV2 strain of the virus was detected in wastewater samples taken in the Khan Younis region in the south of the strip and in areas of central Gaza.

Israel's military campaign in Gaza has killed at least 39,677 people, mostly women and children, and more than 90,000 injured, according to the health ministry.