GENEVA (AFP) - The UN's human rights chief said on Tuesday (Dec 19) that he was "truly shocked" by Israeli troops' killing of a wheelchair-bound Palestinian protester in Gaza, and demanded an "independent and impartial investigation".

Ibrahim Abu Thurayeh, a 29-year-old who lost his legs after an Israeli attack a decade ago, was among five Palestinians killed on Friday during protests against US President Donald Trump's decision to recognise Jerusalem as the capital of Israel.

In a statement, UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein slammed Trump's decision as "dangerously provocative" and blamed it for the violence.

The UN human rights office said Abu Thurayeh was among hundreds of Palestinians who marched across farmland towards the fence separating Gaza from Israel, and appeared to have been shot in the head when he was 20m from the barrier.

"The facts gathered so far by my staff in Gaza strongly suggest that the force used against Ibrahim Abu Thurayeh was excessive," Zeid said.

"As far as we can see, there is nothing whatsoever to suggest that Ibrahim Abu Thurayeh was posing an imminent threat of death or serious injury when he was killed.

"Given his severe disability, which must have been clearly visible to those who shot him, his killing is incomprehensible - a truly shocking and wanton act."

In video footage recorded early on Friday, Abu Thurayeh could be seen carrying the Palestinian flag and waving the victory sign at Israeli soldiers across the border.

Palestinians consider at least part of Jerusalem, which is under full Israeli control, as the capital of their future state and have been infuriated by the decision.

"Israeli security forces have responded with firearms, including live-ammunition, to disperse the protesters," the rights office said.

"These events, including the loss of five irreplaceable human lives, can sadly be traced directly back to the unilateral US announcement on the status of Jerusalem, which breaks international consensus and was dangerously provocative."

While the Israeli army has reportedly conducted a preliminary internal probe into the events, Zeid urged "an independent and impartial investigation" to ensure perpetrators are held accountable.