Israeli troops shot dead three Palestinians in the occupied West Bank on Tuesday, the Palestinian health ministry said, with the Israeli army confirming troops fired on "rioters" who attacked soldiers.

Two brothers were killed by Israeli fire in Kafr Ein, near Ramallah, while a third man died of bullet wounds to the head fired by Israeli troops in Beit Ummar, near the flashpoint city of Hebron, the Palestinian health ministry said.

Commenting on the Beit Ummar clash, the Israeli army said it had opened fire on "rioters" who "hurled rocks and improvised explosive devices at the soldiers" after two vehicles got stuck during an "operation patrol" in the area.

Palestinian official news agency Wafa named the dead man as Mufid Mahmud Khalil, 44, from the Beit Ummar area.

The health ministry identified the dead in Kafr Ein as brothers Jawad Abdulrahman Rimawi, 22, and Dhafer Abdul Rahman Rimawi, 21.

The Israeli army said "a violent riot was instigated by a number of suspects," during "routine" overnight activity in the Kafr Ein area.

"The suspects hurled rocks and Molotov cocktails toward the soldiers, who responded with riot dispersal means and live fire," an army statement said, adding that the military was "aware" of reports of two fatalities.

"The incident is under review," the army said.

Palestinian Authority civil affairs minister Hussein Al Sheikh described the killing of the two brothers as an "execution in cold blood".

Hamas, the Islamist movement which runs Gaza, said the Israeli "escalation" would be "confronted by escalating resistance" from Palestinians.

- Boiling point -

Violence has flared this year in the West Bank, where the Israeli army has launched near-daily raids across the territory.

On Monday, the United Nations envoy for Middle East peace, Tor Wennesland, warned the situation was "reaching a boiling point".

"High levels of violence in the occupied West Bank and Israel in recent months, including attacks against Israeli and Palestinian civilians, increased use of arms, and settler-related violence, have caused grave human suffering," he told the Security Council.

This week, the army announced it had made more than 3,000 arrests this year as part of Operation Break the Wave, a campaign it launched following a series of deadly attacks against Israeli civilians.

The UN says more than 125 Palestinians have been killed across the West Bank this year. Israel has occupied the territory since the Six-Day War of 1967.

Events were planned around the world on Tuesday to mark the UN-sponsored International Day of Solidarity with the Palestinian People.

The latest violence came as veteran hawk Benjamin Netanyahu continued negotiations to form what could be the most right-wing government in Israel's history, following a general election earlier this month.

On Friday, Netanyahu signed an agreement with lawmaker Itamar Ben-Gvir that promised the far-right firebrand the new post of national security minister, with responsibility for the border police in the West Bank.

Ben-Gvir, known for anti-Arab rhetoric, has repeatedly called on police and soldiers to use more force when confronting Palestinian unrest.