JERUSALEM — Unesco, the United Nations cultural organization, declared the ancient and hotly contested core of Hebron in the Israeli-occupied West Bank as a Palestinian World Heritage site in danger on Friday, despite a concerted diplomatic effort by Israel and the United States to scuttle the decision.

The Palestinian Authority administers most of Hebron, a predominantly Palestinian city, under the Oslo peace accords of the 1990s. But an enclave around the historic core remains under full Israeli military control and is also home to several hundred hard-core Jewish settlers.

The area designated as a heritage site includes the Cave of the Patriarchs, an ancient shrine revered by Jews, Muslims and Christians as the burial place of the biblical patriarchs and matriarchs. Muslims refer to the imposing stone structure as the Ibrahimi Mosque, using the Arabic name for Abraham, who, according to the Bible, purchased the cave as a burial plot for his wife, Sarah. He is considered a prophet in Islam.

The Unesco decision, made on Friday by secret ballot, was welcomed by Palestinians, who have lobbied for the move for years. But it was widely criticized by Israel and its allies, who accused Unesco of failing its mandate to foster cultural cooperation.