JERUSALEM, (Reuters) – Israel stopped thousands of Palestinians from entering Jerusalem for Ramadan prayers at the al-Aqsa mosque on Friday and tightened border security as Jews prepared for the solemn annual rite of Yom Kippur.

Israeli police and soldiers at checkpoints near the West Bank cities of Ramallah and Bethlehem turned away several thousand Palestinians who tried to enter Jerusalem for the second weekly prayers of the holy month of Ramadan. Many of those held up at the checkpoints separating the occupied West Bank from Jerusalem knelt in prayer under the glaring sun.

The Israeli army said that no Palestinians from the West Bank, other than exceptional humanitarian cases, would be allowed into the city due to a “high terror threat” until Saturday evening, when the Yom Kippur fasting day ends.

Sheikh Mohammad Hussein, the senior Muslim cleric in Jerusalem, told Reuters that the “arbitrary” Israeli ban “contravenes the freedom of worship”. “They are celebrating their religious holiday at the expense of the Palestinian people,” he said, adding that the al-Aqsa mosque can hold some 200,000 worshippers but he expected the turnout to be much lower because of the Israeli closure.

An Israeli police spokesman said about 30,000 people entered the mosque compound in Jerusalem’s Old City by midday.

Christopher Gunness, a spokesman for the United Nations Relief and Works Agency in the Palestinian territories, also condemned the closure for preventing travel by U.N. workers. He called on Israel to allow the movement of its staff to assist the Palestinian refugee population which is “in an already difficult economic situation”.

Zeinab Deiriya, a 60-year-old Palestinian woman who attempted to cross into Jerusalem, said: “Jews are allowed to celebrate their holidays, but we are banned. The month of Ramadan is sacred for us as much as their sacred holiday.”

Earlier on Friday. Israeli forces wrapped up a three-day incursion into the West Bank city of Nablus where army officers said they arrested several Palestinian militants who were planning a suicide bombing in Israel during the holiday weekend.

Over the 24-hour fast of Yom Kippur — the Day of Atonement — beginning at nightfall on Friday, Israel largely shuts down, with almost no traffic and airports and all businesses closed. The military is on high alert, however, 34 years after Arab armies chose the holiday to launch a surprise attack in 1973.