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 has concluded.

The Palestinian Authority (PA) and Al Jazeera have blamed Israeli forces for Shireen Abu Akleh's killing on the morning of 11 May, 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, aged 51, who was wearing a vest marked "Press" and a helmet, was killed after being hit by a bullet just below her helmet.

Al Jazeera has accused Israeli forces of killing Ms Abu Akleh

The report said Ms 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," Mr Khateeb concluded.

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

Palestinian Attorney General Akram Hassan Al-Khateeb speaks during a press conference in Ramallah

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

Israel's military Chief of Staff Aviv Kochavi said it remains impossible to determine who fired the fatal shot "until we get to the bottom of things".

"There is one thing we can definitively say: No Israeli soldier intentionally fired at the journalist," he said.