Israel's Prime Minister Benjamin Netanyahu said on Saturday his government had "no certainty" that Hamas military chief Mohammed Deif was killed in a strike that officials in Hamas-run Gaza said killed dozens.

"Israel attacked Gaza today in an attempt to eliminate Mohammed Deif and his deputy, Rafa Salama," Netanyahu told a press conference hours after the attack on Al-Mawasi, a designated safe zone in Gaza's south sheltering displaced Palestinians.

"There is no certainty that the two were eliminated," he added.

According to the health ministry in the Hamas-run territory, at least 71 people were killed and nearly 300 wounded in the strike on Al-Mawasi, near the southern city of Khan Younis.

Israel had designated the area a safe zone and told civilians in other areas in Gaza to go there for safety.

Netanyahu described Deif, head of the Hamas military wing, as "the planner and leader" of the October 7 attack that set off the Gaza war.

Netanyahu has vowed to destroy Hamas and bring back all hostages from Gaza.

"The elimination of the heads of Hamas advances the achievement of all our objectives," said the right-wing premier who faces mounting opposition to the conduct of the war.

"In recent weeks, we have identified clear cracks within Hamas," he added.

"Today's operation also contributes to this, regardless of what its outcomes will be." (AFP)