The comments came hours after two Palestinian men were killed by Israeli settlers in a northern village south of Nablus in the latest violent attack involving settlers in the increasingly tense West Bank.
Palestinians said the incident followed a clash when settlers entered Palestinian-owned land and assaulted residents, while settlers said it began with an assault on a Jewish person.
Tensions in the West Bank have escalated sharply since the killing of a 14-year-old boy from a settler family at the weekend.
The violence brought to eight the number of Palestinians killed by Israeli forces or armed settlers since Friday, as Palestinian authorities reported an increasing number of attacks by settlers across the West Bank. Palestinian witnesses and video suggested that Israeli security forces had been present, standing by at some of the incidents.
Salah Bani Jaber, the mayor of Aqraba, a town near the northern city of Nablus, saw Monday’s settler attack. He said about 50 settlers, many of them armed, attacked members of his community and fired at Palestinian youths, killing two of them and wounding others.
“There were Israeli soldiers at the scene who stood idly by watching the settlers,” he said.
The Palestine Red Crescent Society said soldiers blocked its ambulances from reaching the area and tending the wounded. The Israeli military said it was looking into the incident.
In its statement, the UN’s human rights office said that in recent months Palestinians on the West Bank had been “subjected to waves of attacks by hundreds of Israeli settlers, often accompanied or supported by Israeli security forces”.
“In the West Bank, escalating violence over the past few days is also a matter of grave concern,” it added.
“The Israeli security forces must immediately end their active participation in and support for settler attacks on Palestinians,” the rights office spokesperson, Ravina Shamdasani, told reporters in Geneva.
“Israeli authorities must instead prevent further attacks, including by bringing those responsible to account. Dozens of Palestinians were reportedly injured, including through the use of firearms, by settlers and Israeli security forces, and hundreds of homes and other buildings, as well as cars, were torched.
“Three Israeli soldiers suffered injuries after they were hit with stones. It was also reported that settlers established at least two new outposts in the past two days in the Jordan Valley and South Hebron Hills, near Palestinian communities that have been attacked repeatedly by settlers in the past months and are at imminent risk of being forcibly transferred from their homes and land.”
Shamdasani added: “Those reasonably suspected of criminal acts, including murder or other unlawful killings, must be brought to justice through a judicial process that complies with international human rights standards, following a prompt, impartial, independent, effective and transparent investigation.
“This obligation includes protecting Palestinians from settler attacks, and ending unlawful use of force against Palestinians by the Israeli security forces.”
In a statement late on Tuesday, the UK Foreign Office said it was alarmed by “shocking levels of violence” in the occupied West Bank, describing settler attacks as “completely unacceptable”.
“These killings, and subsequent actions, are escalating violence in the Occupied West Bank and the wider region at a critical time. It is vital that Israeli authorities restore calm and conduct urgent and transparent investigations into all deaths, and ensure all violent perpetrators are brought to justice and held accountable for their actions,” the statement said.
The West Bank, which Israel has occupied since 1967, has experienced a rise in violence since early last year. At least 468 Palestinians have been killed by Israeli forces or settlers across the West Bank since the Israel-Hamas war erupted in Gaza on 7 October, according to official Palestinian sources.
The current wave of settler attacks followed the discovery on Saturday by Israeli security forces of the body of an Israeli shepherd, 14-year-old Binyamin Ahimeir, in the central West Bank, who the forces said had been murdered in an anti-Israeli attack.
The situation has prompted the US and the UK to impose sanctions against named violent settlers involved in attempting to drive Palestinian communities from their land against the backdrop of the war in Gaza.
In February the UK imposed sanctions against four Israeli nationals, saying they were “extremist settlers” who had violently attacked Palestinians in the Israeli-occupied West Bank.
The measures impose strict financial and travel restrictions on the four individuals, who Britain said were involved in “egregious abuses of human rights”.
“Extremist Israeli settlers are threatening Palestinians, often at gunpoint, and forcing them off land that is rightfully theirs,” said the UK foreign secretary, David Cameron.
“This behaviour is illegal and unacceptable. Israel must also take stronger action and put a stop to settler violence. Too often, we see commitments made and undertakings given, but not followed through.”
The Foreign Office added that there had been unprecedented levels of violence by settlers in the West Bank over the past year.
Agence France-Presse contributed to this report