Egyptian authorities detained more than 1,100 people since the weekend when protests were held in several cities, calling on President Abdel Fattah el Sisi to quit, human rights monitors said on Wednesday.
Defying a ban on protesting without a permit, hundreds took to the streets in Cairo and other cities on Friday in response to calls for protests against alleged government corruption. The protests continued in the Red Sea city of Suez on Saturday.
Gamal Eid, head of the Arab Network for Human Rights Information, said his own group and two others — the Egyptian Center for Economic and Social Rights and the Egyptian Commission for Rights and Freedoms — had jointly documented more than 1,100 arrests.
The Interior Ministry could not immediately be reached for comment.
Hazem Hosny, a former spokesman for the short-lived 2018 presidential campaign of the ex-military man Sami Anan, was detained on Tuesday evening, said Mustapha Kamel Al Sayyid, a fellow professor at Cairo University, citing Hosny's family.
Sayyid also said Hassan Nafaa, a prominent writer who also teaches at Cairo University, has been missing since 1500 GMT on Tuesday, citing Nafaa's family.
Broad crackdown on dissent
Sisi came to power after leading the overthrow of Egypt's first democratically-elected leader Mohamed Morsi following mass protests against him in 2013.
Protests in Egypt have been rare under Sisi, who has overseen a broad crackdown on dissent that rights activists say is the most severe in the country's modern history.
Sisi's supporters say tough measures were necessary to stabilise Egypt after the turmoil that followed the 2011 uprising that toppled former strongman Hosni Mubarak and replaced him with the Muslim Brotherhood member.
The protests have rattled financial markets, with the Egyptian stock market's main index falling nearly 11 percent in trading between Sunday and Tuesday.
'Sisi is not my president'
On Wednesday morning, the Arabic hashtag "Sisi is not my president" was trending with more than 40,000 tweets.
Several Twitter hashtags have been used to rally support for the protests, while pro-Sisi hashtags have also appeared.
The protests took place after a former civilian contractor for the military, Mohamed Ali, posted a series of videos accusing Sisi and the military of corruption.
Sisi dismissed the allegations as "lies and slander."
Ali has called for mass protests on Friday.