05/23/2014 06:08 pm ET Updated May 23, 2014

New Video Prompts More Scrutiny Of Palestinian Teenagers' Deaths

New footage released on Thursday added to mounting scrutiny over the deaths of two Palestinian teenagers during clashes with Israeli forces in the West Bank last week.

The video shot and published by CNN appears to show Israeli troops firing towards protesters during a demonstration in Beitunia on May 15. The camera then pivots and shows a boy being evacuated from the scene. Nadeem Nawara, 17, was later pronounced dead by Palestinian medics, who said a bullet had pierced his chest. After CNN had left the scene, 16-year-old Mohammad Abu Daher was also fatally shot at the same location.

An Israeli military spokesman told CNN that forces did not use live fire at the protest, which took place during the "Nakba Day" commemoration of Palestinian displacement during Israel's War of Independence in 1948.

But Israel is facing growing pressure to address the boy's deaths after the release of CCTV footage that apparently captured moment they were shot. Earlier this week, advocacy group Defense for Children International published CCTV images that appear to show the teenagers unarmed and calmly walking near fellow protesters, before lurching towards the ground.

Warning: Graphic content

The video prompted the U.S. and a senior United Nations official to call on Israel to launch a credible investigation into the deaths, Agence France Presse reported. State Department spokesperson Jen Psaki told reporters on Tuesday that Washington requested information from the Israeli government about the shootings, and wants a "prompt and transparent" inquiry.

The same day, assistant UN secretary general for political affairs Oscar Fernandez-Taranco told a Security Council 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."

The Israeli military said an initial investigation found no wrongdoing. An army statement said inquiries will continue, but the message cast doubt on the authenticity of the CCTV footage.

The CNN footage released on Thursday raised the stakes. The network also noted that it had reviewed six hours of the unedited CCTV tape, while Israeli newspaper Haaretz also reported Thursday that press photographers at the scene vouched for its authenticity.

Israeli military officials told CNN that rifles shown in their video had been adapted to fire plastic-coated bullets. Rights group B'Tselem on the other hand said it own investigation found the military's account to be "highly incorrect," adding that medical reports and eyewitness testimony disprove the claim that soldiers only fired rubble bullets.