Israeli soldiers unlawfully shot and killed 11 Palestinian civilians, including four children, who were in groups waving white flags during the Gaza war, Human Rights Watch said on Thursday.
"The Israeli military should conduct thorough, credible investigations into these deaths to tackle the prevailing culture of impunity," the New York-based organisation said in a 63-page report.
It said the 11 people were only small fraction of the total number of civilians and combatants killed in the December-January Israeli offensive in the Gaza Strip.
"However, these deaths stand out because the civilians were in groups waving a white cloth, T-shirt or scarf, and no Palestinian fighters were in the area at the time," HRW said.
"Under the laws of war, individuals who carry out or order deliberate attacks on civilians are responsible for war crimes."
In one of the cases mentioned, two women and three children were standing in front of their home after a soldier ordered them outside.
At least three of them were holding pieces of white cloth when a soldier opened fire, killing two girls aged two and seven and wounding the third girl and their grandmother.
"We spent seven to nine minutes waving the flags, and our faces were looking at them," the grandmother, who was shot twice, was quoted as saying. "And suddenly they opened fire and the girls fell to the ground."
In five of the seven incidents detailed in the report, Israeli soldiers shot at civilians who were walking down the street with white flags, trying to leave areas of fighting.
The military said last month it was investigating incidents in which soldiers allegedly killed civilians holding white flags, but HRW charged: "Israel's poor record on investigations makes objective probes unlikely.
"Field investigations typically consist of asking soldiers to question other soldiers, without seeking or considering testimony from external witnesses, and taking exculpatory claims of soldiers at face value," the group said of Israeli military investigations.
The Israeli military is conducting 15 criminal probes into troop conduct during the three-week offensive, including allegations that children were used as human shields.
Israel has said that so far evidence shows troops "pursued legitimate objectives with appropriate precautions," while the Palestinian Hamas group ruling Gaza committed "grave violations of international law."
Earlier this month, HRW published another report on the Gaza war in which it said rocket attacks carried out against Israel by Hamas and other Palestinian militant groups amounted to war crimes.
More than 1,400 Palestinians were killed in the Gaza war, according to Palestinian figures. On the Israeli side 10 soldiers and three civilians were killed either in battle, by friendly fire or by rocket attacks.