Twenty Palestinians were killed Wednesday in the crush of a crowd at a food distribution site run by an Israeli-backed American organization in the Gaza Strip, the group said, the first time it has acknowledged deadly violence at its operations.

Hospitals in Gaza say Israeli airstrikes have killed at least 30 people, including six children at a water collection point.

A crush at an aid centre in southern Gaza killed at least 20 people on Wednesday, with the site's operator blaming "agitators" within the crowd and the Palestinian territory's civil defence agency attributing the panic to Israeli gunfire.