Palestinians say Israeli forces opened fire on people trying to access a U.S.-backed group's aid distribution hub in Gaza, in the deadliest of such incidents reported to date.

Israeli fire killed at least 40 people, half of them near an aid distribution site operated by the U.S.-backed Gaza Humanitarian Foundation on Monday, the territory's health ministry said, as U.N. officials denounced Israeli-backed aid delivery.

Survivors from one of the shootings said Israeli forces began firing on the crowd of hungry Palestinians in the pre-dawn hours.