A young Israeli soldier who shot dead a Palestinian assailant lying wounded and motionless on the ground in the occupied West Bank was convicted of manslaughter on Wednesday in one of the most polarising cases in Israel's history.

The decision to court-martial Sergeant Elor Azaria, who shot the Palestinian after the assailant stabbed another Israeli soldier last March, stirred public controversy in Israel from the start, with right-wing politicians calling after the verdict on President Reuven Rivlin to pardon the 20-year-old defendant.

Prime Minister Benjamin Netanyahu said he supported pardoning Azaria in a post on his Facebook page. A poll published on Wednesday night by Israel's Channel 2 television showed that 67 per cent of respondents favouring a pardon.

“This is a difficult and painful day - first and foremost for Elor, his family, Israel's soldiers, many citizens and parents of soldiers, among them me ... I support granting a pardon to Elor Azaria,” Netanyahu said on his Facebook page.

As the decision was being read at a heavily guarded military court in Tel Aviv, several hundred far-right backers of Azaria - one of them carrying a Donald Trump “Make America Great Again” banner - clashed with police outside the facility.

Ten months ago, Azaria was an army medic serving in the Israeli-occupied city of Hebron when two Palestinians carried out the stabbing. Hebron has been a longtime flashpoint of violence, and the incident occurred during a wave of Palestinian street attacks on Israelis.

One of the two assailants was shot dead by troops. The other was shot and wounded. Eleven minutes later, as the wounded man, Abd Elfatah Ashareef, 21, lay on the ground incapacitated, Azaria shot him in the head with an assault rifle.

At the trial, Azaria contended that he believed the Palestinian, though motionless, still posed a danger because his knife was nearby, and that he might have been carrying explosives. “He deserves to die,” Azaria was quoted in the verdict as telling another soldier after pulling the trigger.

The three-judge panel rejected Azaria's argument.

“One cannot use this type of force, even if we're talking about an enemy's life,” the court said in its verdict.

“We unanimously convict the accused of manslaughter and of conduct unbecoming (a soldier).”

Azaria, who was smiling as he awaited the verdict with his parents beside him, sat emotionless as the chief judge read out the conviction. But his mother screamed “you should be ashamed of yourselves” as the panel left the bench. “Our hero!” relatives of Azaria chanted after the verdict was delivered.

Shooting captured on video

Video footage of the shooting, taken by a Palestinian human rights activist, showed the knife was not within Ashareef's reach, and no bomb was found.

The video was distributed to news organisations, ensuring that the incident drew international attention amid allegations by Palestinians and rights groups that Israeli soldiers have been using excessive force against lightly armed assailants.

Netanyahu took the unusual step of calling Azaria's parents to express his sympathy after the soldier was arrested.

Rallies for Azaria, some backed by rightist politicians and pop singers, gathered momentum as the trial progressed.

In a statement, the self-rule Palestinian Authority's Foreign Ministry said “the occupation's chain of command” must also be prosecuted, accusing it of inciting soldiers to kill.

Sentencing will be handed down at a later date. Azaria's lawyer said they would appeal to a higher military court. The manslaughter charge carries a maximum of 20 years' imprisonment but legal experts expect the sentence to be shorter.