Egyptian security forces fired tear gas and live ammunition into the sky to scatter hundreds of protesters demonstrating on Friday against the government of President Abdel Fattah el-Sisi.
Protesters gathered in the Giza area of Cairo after Friday prayers calling for the overthrow of the "regime", chanting slogans that were common during the 2011 revolution that toppled former president Hosni Mubarak.
"Sisi Mubarak, we don't want you, leave," they yelled.
More than 80 people were arrested in Cairo, Giza and the Mediterranean port city of Alexandria, security officials said.
The protests were the first significant move against Sisi since he was elected president in the summer of 2014.
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Sisi's government announced last week that it had signed a maritime demarcation accord, a move that prompted a public outcry.
A growing number of Egyptians are losing patience over corruption, poverty, and unemployment, the same issues that led to Mubarak's downfall, while Sisi has appeared increasingly authoritarian in televised speeches.
"We want the downfall of regime. We have forced disappearances, all the youth are in jail. I just got out of jail a year ago after two years inside," Abdelrahman Abdellatif, 29, an air-conditioning engineer, told Reuters news agency.
"The youth of the revolution are still here. We are not gone."
Sisi, who came to power after the removal of the Muslim Brotherhood's Mohamed Morsi in 2013, has faced mounting criticism in recent months over a range of issues, including his management of the economy.
A Reuters witness said a crowd was dispersed and riot police had taken control of an area outside a mosque in the Mohandiseen district of the capital. Four people were arrested, security sources said.
Sisi has a large base of support among Egyptians who fear for their security. At a rally Friday in the city of Alexandria, about 500 supporters carried posters with photographs of the president and chanted: "We love you, el-Sisi."
But critics say Sisi's government has mishandled a series of crises, from an investigation into the killing of an Italian student in Cairo to a bomb that brought down a Russian airliner in the Sinai last October.
Calls for protests have gathered thousands of supporters on Facebook, including from the outlawed Muslim Brotherhood.
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