Hundreds of staff members at the U.N. Office of the High Commissioner for Human Rights (OHCHR), led by Volker Turk, have written to urge him to explicitly label Israel's Gaza war as an unfolding genocide, according to a letter.

The staff consider that the legal criteria for genocide in Israel's nearly two-year war on Gaza have been met, citing the scale, scope and nature of violations documented there, the letter, sent on Wednesday and seen by Reuters, said.

"OHCHR has a strong legal and moral responsibility to denounce acts of genocide," said the letter signed by the Staff Committee on behalf of more than 500 employees, which called on Turk to take a "clear and public position."

"Failing to denounce an unfolding genocide undermines the credibility of the U.N. and the human rights system itself," it added.

It cited the international body's perceived moral failure for not doing more to stop the 1994 Rwanda genocide that killed more than 1 million people.