Israel's military has closed its probe into the 2009 shelling of a house in the Gaza Strip that killed 21 members of the Samouni family during Operation Cast Lead.
It said on Tuesday that the civilians had not been purposefully targeted during Israel's three-week war against the Hamas-ruled Gaza Strip, and that the incident did not constitute a war crime.
Witnesses said that on January 4, 2009 Israeli troops had ordered about 100 civilians to enter the house and stay there, out of their way. But the following day the house was hit by Israeli shells and collapsed.
After an investigation into the shelling and allegations of war crimes, the Military Advocate General "found the accusations groundless", the military said in a statement.
"The Military Advocate General also found that none of the involved soldiers or officers acted in a negligent manner," the military said, but added it was making changes to "ensure that such events will not happen again".
Hamdi Shaq-qura, Deputy Director of the Palestinian Center for Human Rights, told Al Jazeera: "Well the decision by military police is not surprising for us. Actually, this is part of systematic denial of justice to Palestinians."
"Over the course of last three years since the war on Gaza in 2008-09, we filed 490 legal cases in the Israeli judiciary, including military judiciary. Out of these only a handful of investigations have been carried," he said.
A UN commission investigating the 22-day Israeli offensive on Gaza put the toll of members of the Samouni family killed in the strike at 29.
Its chairman, South African judge Richard Goldstone, said it was one of the most serious incidents his team investigated.
In 2009, Al Jazeera's Sherine Tadros spoke to members of the Samouni family about what they hoped an investigation would yield
Goldstone has said that Israel's inquiry into the attack found it was apparently due to a commander's misinterpretation of a drone image.
The Israeli group B'Tselem, one of the human rights groups that had submitted the complaint, said the response it received from the military did not detail the findings of the investigation or provide reasons behind the decision to close the file.
"It is unacceptable that no one is found responsible for an action of the army that led to the killing of 21 uninvolved civilians, inside the building they entered under soldiers' orders, even if this was not done deliberately," said Yael Stein, B'Tselem's head of research.
Shaq-qura said: "For us it is not the end of the case. We are still discussing what would be the next step. One of the options is to go to Supreme Court."
"But at the end of the day we have no illusion about the denial of justice before an Israeli court system. But this is a requirement for us to approach international courts."
Israel launched the offensive in late 2008 with the declared aim of ending cross-border rocket fire that continuously struck southern Israel towns.
About 1,400 Palestinians, at least half of them civilians, and 13 Israelis were killed in the invasion.