GENEVA (Reuters) - The U.N. human rights office called on Tuesday for an end to violence in which it said Israeli security forces and Jewish settlers have killed more than 500 Palestinians in the West Bank since the start of the Israel-Hamas war in Gaza.

It said in a statement that Israel had used "unnecessary and disproportionate" force in the Israeli-occupied West Bank, and condemned what it said was the systematic denial of medical aid.

The Israel Defence Forces (IDF) did not immediately respond to a request for comment on the U.N statement.

Violence has surged in the West Bank since the Hamas-led attack on Israel on Oct.7 last year that triggered Israel's military offensive in the Gaza Strip, which the Gaza health ministry says has killed more than 36,000 Palestinians.

Israeli security forces have in recent months cracked down in the West Bank, which Palestinians want as the core of a future independent state along with Gaza, and made thousands of arrests.

Israeli officials have said previously that they are acting to prevent an inflammation of long-running violence in the West Bank, including by Hamas militants, and to prevent attacks on Israel.

U.N. human rights monitors studied 80 cases in-depth among 505 documented deaths of Palestinians in the West Bank since the Oct. 7 attack, in which Israel said about 1,200 people were killed and about 250 were abducted.

The cases studied showed "consistent violations of international human rights law on the use of force by the ISF (Israeli security forces) through unnecessary and disproportionate use of lethal force and an increase in apparently planned targeted killings," United Nations High Commissioner for Human Rights Volker Turk said.

In the same period, 24 Israelis were killed in clashes or reported attacks by Palestinians from the West Bank, the U.N. statement said.

'PERVASIVE IMPUNITY'

Some of the Palestinians killed in the West Bank were children armed with stones or firecrackers and "clearly did not represent an imminent threat to life," it added.

It did not say how many Palestinians had been killed in the West Bank by settlers, and how many by Israeli forces.

The high number of those who died after being shot in the upper part of the body, along with the denial of medical assistance to the injured, suggested an intent to kill, it said.

"Pervasive impunity for such crimes has been commonplace for far too long in the occupied West Bank. Such impunity has created an enabling environment for more and more unlawful killings by the ISF," Turk said.

Hamas runs Gaza and is opposed to coexistence with Israel. The Palestinians Authority exercises limited self-rule in the West Bank.

Settler violence is a source of growing concern among Israel's Western allies. A number of countries, including the United States, have imposed sanctions on violent settlers and urged Israel to do more to stop the violence.

(Reporting by Emma Farge; Additional reporting by Dan Williams in Jerusalem, Editing by Timothy Heritage)

By Emma Farge