Israeli NGO B'Tselem, which monitors human rights abuses in the occupied Palestinian territories, has refuted the Israeli military's claims that no live fire was used against two Nakba Day protesters killed this week.
The organisation said it had found "strong evidence" that IDF soldiers shot "live ammunition" at the protesters.
The incident at Beitunia saw teenagers Nadeem Siam Nawara, 17, and Mohammad Mahmoud Odeh, 16, shot and killed in the chest and back respectively. Two more minors were injured by Israeli gunfire.
B'Tselem has released graphic video footage of the incidents, which cannot be verified independently.
An IDF statement said that live fire was not used and claimed that the video in question was edited to reflect negatively on them.
"Last Thursday, a violent and illegal disturbance took place in Beitunia. The video in question was edited in a biased way and does not reflect the violence in the disturbance," the IDF statement read.
"An initial investigation with the forces operating in the area of disturbance did not use live fire. Nevertheless, the military prosecutor has ordered a limited internal investigation into the matter."
However, an investigation by B'Tselem rejected the IDF's version of events, "finding strong evidence that live ammunition was used and that the fire hit the upper torsos of all four victims.
"The investigation, compounded by security camera footage of the incident, indicate that the circumstances of the incident in no way justified use of live fire. These findings raise grave suspicion that the killing was willful," said the NGO.
The group received medical reports about the entry and exit wounds on both victims which negate the possibility of rubber-coated bullets being used.
The Israeli military's open-fire policies do not allow soldiers to use live ammunition against stone-throwers, unless in grave danger.
The video shows Palestinian protesters throwing stones from a long distance, suggesting that any live fire shots would contravene Israeli military rules.
Both victims were shown not to be throwing stones but to be walking beside the shop when they were shot.
B'Tselem is demanding an investigation into the soldiers' conduct and the "killing of civilians by lethal force".