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.

Violence in Khan Younis adds to wave of attacks that have since May 26 killed hundreds of desperate people seeking food.

Israeli fire killed at least 50 people on Monday, nearly half of them near an aid distribution site run by the U.S.-backed Gaza Humanitarian Foundation, the territory's Health Ministry said, as UN officials denounced Israeli-backed aid delivery methods.