The Hamas-run health ministry in the Gaza Strip said Wednesday it had exhausted its supply of children's vaccines, warning of "catastrophic health repercussions".

The announcement came more than two months into the Israel-Hamas war in Gaza as international aid organisations have warned about the dire conditions in the crowded Palestinian territory.

The ministry did not specify which vaccinations had run out, and its claim could not be independently verified.

Tedros Ghebreyesus, head of the World Health Organization, warned Sunday that "Gaza's health system is on its knees and collapsing," with 14 of 36 hospitals only partially functioning and supplies running low.

"The risk is expected to worsen with the deteriorating situation and approaching winter conditions," he said.

The Gaza health ministry called on international institutions to deliver urgently needed vaccines "to prevent disaster".

Israel has waged a 68-day war against Hamas which rules the Gaza Strip since its gunmen launched the October 7 attacks.

Those attacks killed at least 1,200 people in southern Israel and the militants took around 240 people hostage, according to Israeli officials.

Israel's bombing and ground offensive since has killed over 18,400 people in the Gaza Strip, mostly women and children, according to the health ministry.