Security-camera video showing two unarmed Palestinian teenagers crumpling to the ground, apparently dead, during a lull in a stone-throwing clash with Israeli soldiers revived allegations by human rights activists that the troops often use excessive force.
The Israeli rights group B'Tselem said on Tuesday that the images back its findings that troops killed the teens without cause by firing live rounds from more than 200 metres away. The soldiers were in "zero danger" at the time, said Sarit Michaeli of B'Tselem.
Israeli Defence Minister Moshe Yaalon said: "It was a life-threatening situation, so the officers acted accordingly."
He said he hadn't seen the video, but alleged the images had been manipulated. Lieutenant Colonel Peter Lerner, a senior spokesman, said preliminary findings showed forces fired only rubber-coated steel pellets, a standard means of crowd control, and did not use live fire.
The United Nations and the US State Department called on the Israeli authorities to conduct a transparent investigation.
UN Assistant Secretary General Oscar Fernandez-Taranco told the Security Council's monthly Mideast briefing: "It is of serious concern that initial information appears to indicate that the two Palestinians killed were both unarmed and appeared to pose no direct threat."
At issue is a clash between Israeli troops and Palestinian stone-throwers on May 15 near the West Bank town of Beitouniya, a few hundred metres from an Israeli military base. On that day, Palestinians marked the anniversary of their uprooting in the war over Israel's 1948 creation by holding marches and protests in the West Bank and Gaza.
Starting around midday, several dozen Palestinian youths burned tyres in a main street and threw stones towards Israeli troops, according to witnesses and B'Tselem.
Troops fired rubber bullets but also four live rounds, said resident Fakher Zayed, who said he witnessed the confrontation from his balcony. Four security cameras mounted on Zayed's building captured the events on the street below.
The security footage first surfaced late on Monday when a local advocacy group, Defence for Children International Palestine, released excerpts that it said showed the two fatal shootings. B'Tselem later obtained the unedited footage and said there was no indication the images had been tampered with.
The bodies of the slain teens were taken to Ramallah Hospital. They were identified as Nadim Nawara, 17, and Mohammad Abu Dhaher, 16. B'Tselem later said Abu Dhaher's actual last name was Salameh.
The head of the emergency department, Dr Samir Saliba, said at the time that both were killed by live fire to the upper body. He said Nawara was shot in the chest and Salameh in the right side of his back. A third Palestinian was shot and seriously wounded in the chest, Saliba said.
B'Tselem noted that army rules of engagement barred the use of live rounds at a time when the lives of soldiers were not in danger. Michaeli, the rights group spokeswoman, said the investigation "indicates that the soldiers fired live ammunition at the upper bodies of these youths in conditions where there was no feasible justification for using lethal force against persons".
Michaeli said the circumstances "raise the suspicion of wilful killings".