Updated

Israeli soldiers who fought in last winter's Gaza War say the military used Palestinians as human shields, improperly fired incendiary white phosphorous shells over civilian areas and used overwhelming firepower that caused needless deaths and destruction, according to a report released Wednesday.

The testimonies were by far the strongest allegations to come from war veterans that the army used excessive force during the three-week offensive and echoed claims already leveled by Palestinian and human rights groups. The military rebutted the report, saying the accounts were anonymous and impossible to verify.

The accounts of 26 war veterans were collected by Breaking the Silence, an organization of Israeli army reservists critical of their country's treatment of Palestinians. They described demolishing buildings, vandalizing homes and using more than essential firepower, given the relatively light resistance they encountered. One said the army needlessly used white phosphorous, a masking agent that can cause severe burns, for smokescreens. Others said regulations for opening fire were vague, and that soldiers were expected to do whatever was necessary to protect themselves.

"There were no clear red lines," one soldier told the group. "If you're not sure, kill. Fire power was insane," said another.

Military officers have acknowledged that rules of engagement were relaxed to minimize army casualties but insisted civilians were never targeted.

Israel launched the blistering offensive last December after thousands of rocket attacks by Palestinian militants on southern Israel over an eight-year period. More than 1,400 Palestinians, including at least 900 civilians, were killed in the fighting, thousands of homes were destroyed and Gaza's infrastructure was battered, according to Gaza health officials and human rights groups. Israel puts the death toll closer to 1,100 and says most were armed fighters. Thirteen Israelis were killed, including three civilians who died from rocket fire.

Wednesday's report was sure to fuel a debate that still rages six months after the offensive over whether Israel violated the rules of war. International rights groups, including Human Rights Watch and Amnesty International, have said the degree of force and heavy civilian death toll constituted war crimes, and the U.N. has launched a probe, headed by a respected war crimes prosecutor, into the actions of Israel and Hamas. Human rights groups say Hamas committed war crimes by firing rockets at civilian areas in Israel.

Israel maintains that responsibility for the carnage lies with Hamas, which it says cached ammunition in schools and mosques, blended in with the general population and used civilian areas and public buildings for cover.

The Israeli military said it "regrets the fact that yet another human rights organization is presenting to Israel and the world a report based on anonymous and general testimonies, without investigating their details or credibility." The military also said that since no identifying details were given, it was impossible to verify the accounts. It urged soldiers to come forward and register official complaints.

Defense Minister Ehud Barak reiterated his belief that the Israeli military "is one of the world's most moral armies and operates according to the highest moral code."

Ismail Haniyeh, the leader of the Hamas government in Gaza, said the report "reflects the crimes committed in Gaza," and called on "human rights bodies and international groups" to put Israel's leaders on trial.

Wednesday's 110-page report did not represent a cross-section of soldiers, but rather included troops who approached the group or were reached through acquaintances of group members. Two were junior officers and the rest were lower-ranking personnel. It did not examine Hamas' actions.

Many questioned the overwhelming use of force. One soldier said the army used weapons like mortars and white phosphorous "to show off its strength." Another soldier said white phosphorus artillery shells were used to ignite a house suspected of housing munitions. "The house went up in flames," he said.

Israel has said it used white phosphorus munitions only outside of crowded areas and only as a smokescreen to protect forces. But New York-based Human Rights Watch says Israel fired white phosphorous shells indiscriminately over densely populated areas in what amounts to a war crime.

Breaking the Silence said it decided to protect the identity of the soldiers, noting that many are still in the military and could face punishment for speaking out. But spokesman Mikhael Manekin said the accounts included enough information for the army to figure out which units were involved.

"If there is ever an inquiry, the witnesses will gladly testify," he said. An internal military probe earlier this year found no systematic wrongdoing on the part of the army.

A few other soldiers have come forward with similar second-hand testimony since the operation. But overall, the Israeli public believes the Gaza operation was necessary to halt the rocket fire and think their military is singled out for unfair criticism.

Some testimonies provided a glimpse at the complex battlefield the soldiers faced as they pushed into densely populated territory, fearing booby-trapped houses and alleyway ambushes and unable to tell civilians from combatants. Hamas had promised to make Gaza a "graveyard" for the Israelis.

One soldier quoted his commander as saying "I am not willing to allow a soldier of mine to risk himself by hesitating."

But most focused on what they saw as improper behavior, like the vandalism of Palestinian property or the use of civilians as human shields — a practice the army itself has banned.

"Sometimes the force would enter while placing rifle barrels on a civilian's shoulder, advancing into a house and using him as a human shield. Commanders said these were the instructions and we had to do it," one soldier said.

Another said that soldiers would shoot at houses and water tanks from boredom.

"At one point, an officer decided to give a grenade-throwing training exercise. He put the soldiers in a house and they threw grenades inside until it was completely destroyed," he said. Other accounts described soldiers drawing X-rated graffiti on the walls of occupied houses, or using bulldozers to systematically destroy homes.