Protesters have broken into the building housing Israel's embassy in Egypt's capital, Cairo.
A security official said the protesters were in a flat below the embassy, but had not entered the mission itself.
Israel has asked for US help to protect its embassy, Israeli Defence Minister Ehud Barak said.
There have been protests outside the embassy since the deaths on 18 August of five Egyptian policemen, allegedly at the hands of Israeli forces.
Egyptian officials say the five were killed as Israeli forces chased suspected militants across the border.
Gunmen had earlier that day attacked Israeli civilian buses near the Red Sea resort of Eilat, killing eight people.
Hundreds of Egyptians protested outside the Israeli embassy in Cairo the following night, burning the Israeli flag and demanding the expulsion of the Israeli ambassador.
Peace treaty tested
On Friday, protesters destroyed a wall around the embassy building before a group of about 30 broke in and threw documents out of windows.
Reuters news agency quoted an Israeli official in Jerusalem as saying that the documents appeared to be "pamphlets and forms kept at the foyer". Egypt's state media said some of the documents were marked confidential.
Officials at Cairo's airport said the Israeli ambassador was there, waiting to catch a flight out of Egypt.
A statement from Mr Barak's office said he had spoken with US Defence Secretary Leon Panetta and had "asked them to protect the embassy from the demonstrators".
US President Barack Obama has appealed to Egypt to honour its international obligations and protect the embassy, the White House said in a statement.
Mr Obama had spoken to Israeli Prime Minister Benjamin Netanyahu and said the US was taking steps to help resolve the situation without further violence, the White House statement said.
Following last month's border incident, Cairo called the policemen's death "unacceptable". Israel did not admit responsibility, but said the deaths were regretted. Israel's defence minister said he had ordered a joint inquiry to be held with the Egyptian army.
Correspondents say the incident marked a sharp escalation in tensions between Israel and Egypt. Their 30-year-old peace treaty was already being tested after the long-time Egyptian leader, Hosni Mubarak, was forced from office earlier this year.
Under Mr Mubarak, ties between the two nations had been stable after a history of conflict.
But his removal has sparked fears among Israeli officials that a less amenable government could take charge in Cairo.
A security official said the protesters were in a flat below the embassy, but had not entered the mission itself.
Israel has asked for US help to protect its embassy, Israeli Defence Minister Ehud Barak said.
There have been protests outside the embassy since the deaths on 18 August of five Egyptian policemen, allegedly at the hands of Israeli forces.
Egyptian officials say the five were killed as Israeli forces chased suspected militants across the border.
Gunmen had earlier that day attacked Israeli civilian buses near the Red Sea resort of Eilat, killing eight people.
Hundreds of Egyptians protested outside the Israeli embassy in Cairo the following night, burning the Israeli flag and demanding the expulsion of the Israeli ambassador.
Peace treaty tested
On Friday, protesters destroyed a wall around the embassy building before a group of about 30 broke in and threw documents out of windows.
Reuters news agency quoted an Israeli official in Jerusalem as saying that the documents appeared to be "pamphlets and forms kept at the foyer". Egypt's state media said some of the documents were marked confidential.
Officials at Cairo's airport said the Israeli ambassador was there, waiting to catch a flight out of Egypt.
A statement from Mr Barak's office said he had spoken with US Defence Secretary Leon Panetta and had "asked them to protect the embassy from the demonstrators".
US President Barack Obama has appealed to Egypt to honour its international obligations and protect the embassy, the White House said in a statement.
Mr Obama had spoken to Israeli Prime Minister Benjamin Netanyahu and said the US was taking steps to help resolve the situation without further violence, the White House statement said.
Following last month's border incident, Cairo called the policemen's death "unacceptable". Israel did not admit responsibility, but said the deaths were regretted. Israel's defence minister said he had ordered a joint inquiry to be held with the Egyptian army.
Correspondents say the incident marked a sharp escalation in tensions between Israel and Egypt. Their 30-year-old peace treaty was already being tested after the long-time Egyptian leader, Hosni Mubarak, was forced from office earlier this year.
Under Mr Mubarak, ties between the two nations had been stable after a history of conflict.
But his removal has sparked fears among Israeli officials that a less amenable government could take charge in Cairo.