A senior Palestinian official on Tuesday accused Israel of the "deliberate execution" of two Palestinian teens shot dead by border policemen in a clash in the West Bank last week.
But an Israeli army spokesman told AFP that video footage purporting to show the two being killed without provocation on Thursday had been doctored.
"In the strongest possible terms, we condemn the deliberate execution of two Palestinian teenagers who were fatally shot with live ammunition outside Ofer prison last week," the Palestine Liberation Organisation's Hanan Ashrawi said in a statement.
"Both boys were unarmed and posed no direct or immediate threat."
"Israel's use of excessive and indiscriminate violence and live ammunition at non-violent Palestinian demonstrations constitutes war crimes and crimes against humanity under international law," she said.
The military said at the time that the border police used "anti-riot means and rubber bullets" against a violent demonstration by about 150 Palestinians.
Defence for Children International Palestine has released what it said was CCTV footage showing the deaths of Musaab Nuwarah, 20, and Mohammed Udeh, 17, during Thursday's demonstration near the prison marking the 66th anniversary of the Nakba -- or "catastrophe" -- of the Jewish state's creation.
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The video can be seen on the Swiss-based non-governmental organisation's website.
It is interspersed with an account of events by a Palestinian man.
"That film was edited and does not reflect the reality of the day in question; the violence," Major Arye Shalicar, an Israeli army spokesman, told AFP.
The border police contingent was under the army's command at the time of the incident.
"As part of our enquiry we have investigated whether there was live fire and we have not found that there was live fire," he said. "We are continuing with our investigation."
Amnesty International has denounced the Israeli army's "excessive" use of force in the Ofer incident.
"The Israeli army and border police used excessive, including lethal, force in response to rock-throwing protesters who could not have posed a threat to the lives of the soldiers and policemen in or near the fortified military camp," the rights watchdog said last week.