An Al Jazeera journalist killed in the occupied West Bank earlier this month was murdered by an Israeli soldier in a "war crime", the official Palestinian investigation concluded Thursday.

The Palestinian Authority (PA) and Al Jazeera have blamed Israeli forces for Shireen Abu Akleh's killing on the morning of May 11, when she was covering an Israeli army operation in Jenin camp in the north of the West Bank. 

All "proven facts constitute the elements of the crime of murder... according to national laws, they are a war crime and a violation of international laws," said PA attorney general Akram Al-Khateeb, who presented the Palestinian investigation's findings.

The Palestinian-American journalist, who was wearing a vest marked "Press" and a helmet, was killed after being hit by a bullet just below her helmet.

The report said Abu Akleh was killed with a 5.56 millimetre armour piercing round fired from a Ruger Mini-14 rifle.

The report also said that bullet holes on a nearby tree indicated the "targeting of the upper parts of the body with the aim of killing."

"All of these facts: the type of projectile, the weapon, the distance, the fact that there were no obstructions to vision and that she was wearing a press jacket lead us to conclude that (Shireen) Abu Akleh was the target of a murder," Khateeb concluded.

"The only source of fire was the Israeli occupation forces," he said.

Senior PA official Hussein al-Sheikh said a copy of the report had been sent to US authorities, while copies would also be given to Abu Akleh's family and Al Jazeera.

Israeli authorities were quick to decry the report's conclusions, with Defence Minister Benny Gantz saying that the Israeli army would never target journalists.

"Any claim that the IDF intentionally harms journalists or uninvolved civilians, is a blatant lie," he said in a statement, referring to the Israeli Defence Forces.

"Despite the Israeli side reaching out repeatedly, the Palestinians refuse to cooperate, which raises the question (of) if they really want to reach the truth," he said.

Palestinian authorities had refused to hand the bullet over to Israeli authorities for further investigation, citing a lack of trust.

Israeli authorities have said that Abu Akleh could have been killed by stray fire from a Palestinian gunman in the area or mistakenly by an Israeli soldier.