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Police took up positions throughout Jerusalem's Old City on Tuesday as Israeli archaeologists began digging near a site holy to both Jews and Muslims amid protests and threats from Palestinians.

The Israel Antiquities Authority said the work poses no danger to the holy site. Palestinians fear Israel will damage it and have warned the work would inflame tensions.

Palestinians clashed with Israeli forces in several areas of Jerusalem and the West Bank, though no injuries were reported. Palestinian leaders harshly condemned the project.

"What is happening is an aggression," Mohammed Hussein, the mufti of Jerusalem, told the Gaza Strip radio station of the Hamas militant movement. "We call on the Palestinian people to unite and unify the efforts to protect Jerusalem."

The dig is just outside one of the most sensitive places in the Mideast conflict — the hilltop in the heart of Jerusalem that is known to Jews as the Temple Mount and to Muslims as the Noble Sanctuary. The site often has been the catalyst of Israeli-Palestinian fighting.

Israel plans to build a new pedestrian ramp to the complex and says it wants to ensure the renovation work does not come at the expense of important artifacts. Such exploratory digs are common practice in the ancient city.

The ramp will replace a centuries-old walkway that was damaged in a snowstorm three years ago.

"The construction of the bridge, located in its entirety outside the Temple Mount, has no impact on the Mount itself and certainly poses no danger to it," Prime Minister Ehud Olmert's office said.

Yuval Baruch, Israel's chief archaeologist for the Jerusalem region, told Israel Radio Tuesday that the work was between 60 to 70 yards from the site, and that there was "no intention of getting close to the Temple Mount."

"We invite everyone to come see. We are working under the open sky and have nothing to hide. We won't do anything secretly or in the dark," Baruch said.

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On the first day of work, however, access was heavily restricted.

Police spokesman Shmuel Ben-Ruby said police were stationed in alleys throughout the Old City and at the entrances to the disputed compound "to thwart any attempt to disrupt order."

Police also prevented tourists from entering the site, and restricted access for Muslim men to Israeli Arabs and east Jerusalem residents over the age of 45.

Jews revere the Mount as the site of their two biblical temples. Muslims believe it's where the Prophet Muhammad ascended to heaven during a nighttime journey recounted in the Koran, the Muslim holy book. Two mosques — the Al-Aqsa and Dome of the Rock — now stand on the site, along with some of the temples' original retaining walls, including the Jewish shrine called the Western Wall.

"The continued Israeli aggression on Al-Aqsa mosque and Jerusalem require all Palestinians to unite and remember that our battle is with the occupation," said Prime Minister Ismail Haniyeh of Hamas. He spoke as he departed for Saudi Arabia for reconciliation talks with President Mahmoud Abbas of the rival Fatah faction.

Fighting between Hamas and Fatah has claimed more than 130 lives since May. But Palestinians were united in their opposition to the Israeli renovation project.

Islamic Jihad, a small and violent group funded by Syria and Iran, said it fired two rockets from Gaza into southern Israel to protest the construction. The army said the rockets caused no damage.

Earlier, Islamic Jihad, which has carried out dozens of suicide bombings, warned it would "shake the land underneath the legs of the Zionists" and that Israel was "opening the door for a new war with the Islamic nation."

The Al Aqsa Martyr's Brigades, a Fatah-linked militant group, weighed in with similar fiery threats, along with Hamas' Qassam Brigades. Raed Salah, the fiery leader of the Islamic Movement inside Israel, called on his followers to come from all over the country to protect the site.

"The danger in Jerusalem has increased. It is high time for the intifada of the Islamic people," Salah told reporters near the holy site on Tuesday.

Adnan Husseini, the director of the Islamic Waqf, the trust that oversees that complex, said he was concerned the new walkway could damage the original earthen ramp, which he said was Waqf property.

"This is a very dangerous project that will damage things of great historical value in this very sensitive place," Husseini said.

He said he suspected Israel of trying to tunnel under the site, a common allegation among Muslims, though one never substantiated.

When Israel opened a tunnel alongside the complex in 1996, it touched off clashes that killed 80 people. In 2000, then-opposition leader Ariel Sharon visited the site. The next day, riots erupted, leading to years of violence.

Jordan, which has a custodial role over the site, expressed concern about the work there, according to the kingdom's official Petra news agency.

Jordanian government spokesman Nasser Judeh quoted Prime Minister Marouf al-Bakhit as saying that the dig was "a big concern to Jordan, its king, people and government," Petra reported.

The site is part of east Jerusalem, which was ruled by Jordan until Israel captured it and the adjacent West Bank in the 1967 Mideast war.

In 1988, the current's king's father, King Hussein, renounced his country's claim to the West Bank, but maintained Jordan's authority to look after the mosques — a role that Israel recognizes.

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