At least 120 people were injured when Egyptian security forces fired tear gas and rubber-coated steel bullets at pro-Palestinian protesters who were trying to storm the Israeli embassy in Cairo.
Thousands of protesters had gathered outside the embassy in the capital on Sunday to commemorate the 63rd anniversary of the "Nakba" or "catastrophe" - the day Israel declared its independence and hundreds of thousands of Palestinians fled or were expelled from their homes.
Witnesses said a group of demonstrators later tried to storm the entrance of the embassy, prompting the police's response. At least 20 people were arrested.
Al Jazeera's Rob Gilles, who was at the scene, said that some protesters responded by burning tires in the middle of the road and throwing stones.
"The security forces have made a charge outside the embassy to clear the street in front of it and most of the protesters are being forced back," he said.
"They've sealed off the main area into it but there is still a determined presence here; they are determined not to move, spurred on by the images they've seen of the Nakba protests in other parts of the Middle East.
"We've seen a few people laid out on the floor, mainly suffering from gas inhalation more than anything else."
Activists had earlier called for marches to start on Sunday to reach the Rafah border crossing between Egypt and the Gaza Strip.
The incident followed the visit to Egypt by a senior Israeli defence ministry official - the first trip by a top Israeli official since a popular uprising toppled former president Hosni Mubarak in February.
Amos Gilad was to hold talks with several Egyptian officials "to discuss the latest developments in the region, in light of the Palestinian reconciliation agreement", MENA, Egypt's state news agency, reported on Sunday.
Palestinian president Mahmoud Abbas and Hamas leader Khaled Meshaal ended a four-year feud at a reconciliation ceremony in the Egyptian capital, Cairo, earlier this month. Israeli prime minister Binyamin Netanyahu called the deal "a tremendous blow to peace".
The long-awaited accord, agreed by 13 factions, aims to put a stop to the animosity which has split the Palestinian territories into opposing camps since 2007.
The agreement envisages Hamas and Fatah working to put together an interim government of candidates who are unaffiliated with either faction, who would govern until presidential and legislative elections within a year.