Two Israeli soldiers have alleged that they were ordered to carry out revenge attacks on Palestinian police after six of their comrades were killed.
The Israeli army says it targeted only police who helped militants
The unnamed soldiers made the charges, which relate to events three years ago, to an organisation which gathers evidence on Israeli army abuses.
At least 15 Palestinians were killed in response to the troops' deaths.
The Israeli army said it had targeted policemen who actively assisted militants in carrying out killings.
But it is not clear whether the Palestinians killed had actually aided militants.
Correspondents say the report is a challenge to Israel's insistence that it abides by a strict code of ethics and has avoided tit-for-tat killings.
'No concrete evidence'
The first soldier, who describes himself as a sergeant in a reconnaissance unit, was quoted on the website of Breaking the Silence, a group set up by former soldiers to document evidence of abuses by the Israeli Defence Force.
He said his squad was summoned by their commander after the killings of six Israelis at a checkpoint near Ramallah in the West Bank.
He told them their task was to kill six Palestinians in revenge.
The soldier was told that there was a suspicion that the militants responsible had been allowed through a Palestinian police checkpoint, which was to be the target of their attack.
But there was no concrete evidence of this, he said.
"I was told: 'It doesn't matter - they took six of ours, and we are going to take six of theirs,'" he said.
The sergeant said the group ambushed the Palestinians, killing three. A fourth man escaped.
"I really enjoyed it," he said. "It was the first time that we were in an 'advance storm' situation, like in our training exercises.
"And we acted flawlessly. We performed superbly."
The soldier added that several of his comrades kept shooting at one of the bodies, "punching holes in it".
A second soldier, from paratroop reconnaissance, was quoted by the UK Guardian newspaper as saying that he was told to attack three checkpoints in the Nablus area and simply shoot at police.
It was clearly a revenge attack, he said.
At least two Palestinians were killed in the raid.
BBC Jerusalem correspondent James Reynolds says the allegation that revenge was the motive for the army's raid is nothing new.
The day after the attack Israel's leading newspaper Yediot Ahronot described the army's actions as "fierce acts of revenge".
And in a statement the Israeli army does not deny that members of the Palestinian policemen were killed in the wake of the troops' deaths.
The army alleges it had become apparent that Palestinian security forces were heavily involved in militant activities.
"It was decided that the IDF will hunt down all those involved in terror activities, including members of the PA security apparatus, until such time as the PA accepts responsibility for the areas under its control and prevents the terror attacks emanating from Palestinian towns and cities," it said.
Michael Tarazi, a legal advisor to the Palestinian Authority questioned why Israel chose to kill rather than arrest the men if it had evidence implicating them in militant attacks.
He told the BBC News website Palestinians have long accused Israeli forces of brutality and of carrying out revenge attacks "but their claims tend to be dismissed".