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Hundreds of thousand of protesters gathered in cities across Egypt on Friday to condemn Israel's bombardment of Gaza, which has killed more than 4,000 Palestinians.
Al Nasr Street in the Nasr City district of Cairo was among the designated protest sites.
But tens of thousands demonstrated across the city, with some breaking through police barricades to reach areas including Tahrir Square.
“The police tried to block us from entering the actual square, but there were so many people pushing through, they just decided to let them through. I haven't seen the square so full of people in a long time,” Ingy El Sayed, 28, who participated in Friday's protests, told The National.
The square was the scene of one of the largest demonstrations on Friday, while thousands also gathered in historic districts of Islamic Cairo and its famed Al Azhar Mosque.
At least 28 protesters were arrested in and around Tahrir Square following clashes with security officers, police officials told The National. The protesters threw rocks at the officers before being apprehended, police said.
Since the start of Israel’s bombardment of the Gaza Strip, demonstrations have been held around the world.
Some of the largest were held in cities including Cairo. Armoured vehicles arrived at the protest areas on Friday to help maintain security.
“With our souls and our blood, Gaza will not be lost,” protesters chanted in Nasr City on Friday.
In Tahrir Square, crowds also chanted “bread, freedom, social justice”, a slogan made popular during 2011 demonstrations that led to Hosni Mubarak being ousted as president.
Prominent opposition figures attended the protest in Tahrir Square, including Gameela Ismail, who in September said she was a candidate for the presidential elections, only to withdraw this month.
Some protesters on Al Nasr Street had their bodies painted with the colours of the Palestinian flag.
“This is injustice and it has to stop. They can’t keep treating Arabs and Muslims like rats and expect us to do nothing in return,” said Ali Ahmed, 26, a resident of Nasr City.
“We will not be silenced now that the President is with us on this. We will go out on the street and call for an end to Israel’s butchery every day for however long it takes.”
Mr El Sisi, who will run against three opponents in December's presidential election, has enjoyed a surge in popularity following a number of impassioned speeches on the war.
The government had been facing criticism for an economic downturn in which inflation rose to record highs and the local currency lost half of its value.
Another demonstration was held at the Rafah crossing on Friday, ahead of the arrival of UN Secretary General Antonio Guterres.
He visited he Egypt-Gaza border crossing to oversee preparations for 20 lorries to carry aid into the Palestinian enclave.
Mr Guterres gave a two-minute address that was regularly interrupted by loud chants from protesters denouncing the war on Gaza.
A witness told The National that the demonstrators approached Mr Guterres, whose security team led him to his car, which took him back to Arish.