Geneva, Switzerland - The UN human rights chief on Thursday decried allegations of serious rights violations in the Israel-Gaza war and suggested an international investigation was needed.

Volker Turk said "extremely serious allegations of multiple and profound breaches of international humanitarian law, whoever commits them, demand rigorous investigation and full accountability".

Turk was speaking after a visit last week to the Middle East, where he warned that both sides were committing war crimes in the deadly conflict.

"Where national authorities prove unwilling or unable to carry out such investigations, and where there are contested narratives on particularly significant incidents, international investigation is called for," he said in a briefing to UN member states in Geneva.

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It was vital, he told reporters later, for his office to access the Palestinian territories "to ensure full and independent monitoring and documentation and to coordinate the protection work".

He said he had "asked Israel to give me access both to Israel, but also to the occupied Palestinian territory. I have not yet received a response".

Israel has vowed to eradicate Hamas in retaliation for the attacks of October 7, which killed 1,200 people, most of them civilians.

Hamas also took around 240 people hostage, among them elderly people and young children.

A brutal bombardment and ground offensive in Gaza has killed more than 11,500 people at the last count, mainly civilians and including thousands of children. Hospitals have been targeted, with Israel still raiding Al-Shifa, the strip's largest medical facility – where thousands are sheltering – over as-yet unproven claims that Hamas is using it as an operational center.

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But Turk told member states the crisis extended well beyond the Gaza Strip and voiced deep concern about the "intensification of violence and severe discrimination against Palestinians in the occupied West Bank, including East Jerusalem".

"This creates a potentially explosive situation and I want to be clear: we are well beyond the level of early warning," he said. "I am ringing the loudest possible alarm bell about the occupied West Bank."

He urged an immediate ceasefire and called on all parties to acknowledge the equal value of all human lives, insisting that "the Israeli occupation must end."

Since October 7, nearly 200 Palestinians have been killed by Israeli authorities and extremist settlers in the West Bank, which is not controlled by Hamas.