JERUSALEM — With dozens of policemen looking on, an Israeli bulldozer began work yesterday on an archaeological excavation next to the Holy Land’s most explosive religious site, drawing protests from Palestinian Arabs and condemnations from the Arab world.

Muslims are angry at Israel’s plan to build a new walkway up to the compound where Islamic tradition says the Prophet Muhammad ascended to heaven and which Jews revere as the site of their two ancient temples.

Israel says the project is needed to replace a centuries-old earthen ramp that partially collapsed in a snowstorm three years ago. But its assurances that the work would cause no harm to Islam’s holy sites did little to soothe tensions.

Palestinian Arab leaders harshly condemned the project, and Palestinian Arabs clashed with Israeli security forces in several areas of Jerusalem and the West Bank. No injuries were reported.

“What is happening is an aggression,” Mohammed Hussein, the top Islamic cleric in 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 50 yards from the walls of the hilltop compound in Jerusalem’s Old City known to Jews as the Temple Mount and to Muslims as the Noble Sanctuary. Palestinian Arabs and Israelis have clashed there in the past.

The dig is meant to ensure no important artifacts are damaged by the walkway’s construction, which is expected to be completed in eight months. Such exploratory digs are required by Israeli law in the ancient city.

“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 Olmert’s office said.

There is nothing “that can cause damage to the walls of the Temple Mount, and certainly not to any structures inside,” the archaeologist in charge of excavations and surveys at the Israeli Antiquities Authority, Gideon Avni, said.

Yesterday, the first day that employees began dismantling the original ramp, security forces were on high alert. Police spokesman Micky Rosenfeld said 2,000 officers were stationed around the Old City and east Jerusalem, more than double the normal deployment.

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

“Every stone they make fall from its place is a part of my soul,” said Nidal Abu Shaha, 41, one of several Palestinian Arabs watching the bulldozer. “Every part of Al Aqsa is holy, including this ramp.”

There were no disturbances at the site, but Palestinian Arab protesters threw stones at police in three other parts of Jerusalem, causing no injuries, police said.

In the West Bank town of Bethlehem, about 200 Palestinian Arabs threw stones and bottles at an Israeli checkpoint. In the Gaza Strip, radio stations played songs about Jerusalem, and Hamas held a rally attended by thousands. Egypt’s Muslim Brotherhood also condemned the work.