Israel's occupation and discrimination against Palestinians are the main causes of the endless cycles of violence, UN investigators said Tuesday, prompting angry Israeli protests.

A high-level team of investigators, appointed last year by the United Nations Human Rights Council to probe "all underlying root causes" in the decades-long conflict, pointed the finger squarely at Israel.

"Ending the occupation of lands by Israel... remains essential in ending the persistent cycles of violence," they said in a report, decrying ample evidence that Israel has "no intention" of doing so.

The 18-page report mainly focuses on evaluating a long line of past UN investigations, reports and rulings on the situation, and how and if those findings were implemented.

Recommendations in past reports were "overwhelmingly directed towards Israel," lead investigator Navi Pillay, a former UN rights chief from South Africa, said in a statement.

This, she said, was "an indicator of the asymmetrical nature of the conflict and the reality of one state occupying the other".

The investigators also determined that those recommendations "have overwhelmingly not been implemented", she said, pointing to calls to ensure accountability for Israel's violations of international law but also "indiscriminate firing of rockets" by Palestinian armed groups into Israel.

"It is this lack of implementation coupled with a sense of impunity, clear evidence that Israel has no intention of ending the occupation, and the persistent discrimination against Palestinians that lies at the heart of the systematic recurrence of violations in both the Occupied Palestinian Territory, including East Jerusalem, and Israel."

- 'Witch hunt' -

Israel has refused to cooperate with the Commission of Inquiry (COI) created last year following the 11-day Hamas-Israel war in May 2021, which killed 260 Palestinians and 13 people on the Israeli side.

Israel has in the past loudly criticised Pillay for "championing an anti-Israel agenda", and on Tuesday the foreign ministry slammed the entire investigation as "a witch hunt".

The report, it said, was "one-sided" and "tainted with hatred for the State of Israel and based on a long series of previous one-sided and biased reports."

It had been published, it said, as "the result of the Human Rights Council's extreme anti-Israel bias."

The United States, a staunch ally of Israel -- which rejoined the Council under President Joe Biden, after Donald Trump withdrew from the body -- reiterated that it "firmly" opposes the "open-ended and vaguely defined nature" of the COI.

"The existence of this COI in its current form is a continuation of a long-standing pattern of unfairly singling out Israel," State Department spokesman Ned Price said in a statement.

In Geneva, dozens of Israeli reserve soldiers and students -- some of them dressed like Palestinian Hamas militants -- marched Tuesday outside the UN headquarters in protest.

Nitsana Darshan-Leitner, who heads the Israeli NGO Shurat Hadin that organised the protest, slammed the rights council as "the most anti-Semitic body in the world."

Israel and its allies have long accused the top UN rights body of anti-Israel bias, pointing among other things to the fact that Israel is the only country that is systematically discussed at every regular council session, with a dedicated special agenda item.

The COI, which is the highest-level investigation that can be ordered by the council, is the ninth probe it has ordered into rights violations in Palestinian territories.

It is the first, however, tasked with looking at systematic abuses committed within Israel, the first open-ended probe, and the first to examine "root causes" in the drawn-out conflict.