The UN human rights chief has slammed Israel's deadly reaction to protests along the Gaza border as "wholly disproportionate", backing calls for an international investigation

Opening a special session of the UN Human Rights Council that could set up a commission of inquiry into recent Israeli violence that has resulted in deaths of more than 100 Palestinians in six weeks, Zeid Ra'ad al-Hussein warned that "killing resulting from the unlawful use of force by an occupying power may also constitute wilful killings, a grave breach of the Fourth Geneva Convention."

He went on to say that Israel has systematically deprived Palestinians of their human rights, with 1.9 million in Gaza "caged in a toxic slum from birth to death".

"Nobody has been made safer by the horrific events of the past week," he added. "End the occupation, and the violence and insecurity will largely disappear."

He pointed out though that while at least 60 Palestinians were killed and thousands injured in a single day of protests on Monday, "on the Israeli side, one soldier was reportedly wounded, slightly, by a stone".

"The stark contrast in casualties on both sides is ... suggestive of a wholly disproportionate response," he told the council.

Many of the Palestinians injured and killed "were completely unarmed, (and) were shot in the back, in the chest, in the head and limbs with live ammunition," he said, saying there was "little evidence of any (Israeli) attempt to minimise casualties".

"Although some of the demonstrators threw Molotov cocktails, used slingshots to throw stones, flew burning kites into Israel and attempted to use wire-cutters against the two fences between Gaza and Israel, these actions alone do not appear to constitute the imminent threat to life or deadly injury which could justify the use of lethal force."