Thousands of Egytian journalists have demanded the sacking of the country's interior minister for a raid on the press syndicate and arrest of two journalists.
Most Egyptian newspapers on Thursday ran the interior minister's picture in negative with a black banner on their front pages as part of the anti-government protest, the DPA news agency reported.
Protesters say Magdy Abdel Ghaffar is responsible for the security services' raid on the syndicate that led to the arrest of journalists Mahmoud el-Sakka and Amr Badr.
The operation against the organisation was the first in its 75-year history.
Chanting "journalism is not a crime", the reporters decided to hold a meeting next week to discuss organising a strike if their demands were not met, union officials said.
On Monday, the public prosecutor said Sakka and Badr were being investigated for "spreading news based on lies" and possession of firearms, among other accusations.
The interior ministry has denied its officers stormed the union building but confirmed it had arrested the two inside the building.
The prosecutor's office issued a gag order on Tuesday on the case of the two journalists and the circumstances of their arrest. Syndicate officials said on Wednesday they would challenge it in court.
Dozens of pro-government demonstrators gathered outside the syndicate in downtown Cairo, calling for President Abdel Fattah al-Sisi to "slaughter" the journalists as they entered and exited the building, according to a Reuters witness.
The journalists' protests come at a time when Sisi also faces criticism because of the struggling economy and many question whether he continues to enjoy the broad public support that allowed him to round up thousands of opponents after he seized power in 2013.