The soldiers also heard "hostages" shouted in Hebrew on December 10, but interpreted that as a "terrorist deception attempt" by Hamas militants to lure them into the building in the Gaza City district of Shejaiya, the probe said.

Believing the building was rigged with explosives, the soldiers exited and killed five Hamas militants trying to escape, it added.

The hostages then probably fled the building also, and on December 15 Israeli soldiers shot them after mistakenly identifying them as a threat, the investigation said.

Two were killed instantly. The third hostage fled and soldiers were ordered to hold fire in order to identify him, the probe said.

Hearing cries of "help!" and "they're shooting at me", Israeli commanders asked the surviving hostage to advance towards the soldiers.

But two soldiers "who did not hear the order" because of "noise" from a nearby tank shot him dead.

The three hostages were all shirtless and one had been carrying a white flag.

On December 14, an army drone had identified signs of "SOS" and "help, three hostages" on a building close to where the three hostages were shot.

The army "failed in its mission to rescue the hostages in this event," army chief Herzi Halevi said in a statement published along with the report of the investigation.

The three fatalities "could have been prevented", he added.

Soon after the killings of the hostages were announced, Prime Minister Benjamin Netanyahu said it "broke my heart" and "broke the whole nation's heart".

Israel has been mourning the deaths of the hostages identified as Yotam Haim, Alon Shamriz and Samer El-Talalqa.

The killings of the three men, all in their twenties, have sparked protests in Tel Aviv, where demonstrators demanded that the authorities come up with a new plan to bring home the remaining 129 hostages still held in the Gaza Strip.

About 250 people were taken hostage during Hamas's October 7 attacks in Israel, which resulted in the deaths of around 1,140 people, mostly civilians, according to an AFP tally based on Israeli figures.

Vowing to destroy Hamas and bring back the hostages, Israel launched a massive military offensive against the Palestinian Islamist movement that has left much of Gaza in ruins.

The territory's Hamas government says the war has killed at least 21,320 people, mostly women and children.