Egyptian riot police on Wednesday cordoned off the headquarters of the journalists' union and limited access to the building in an escalating standoff following a raid on the premises and the arrest of two journalists.
Dozens of journalists rallied outside the union headquarters on Wednesday, chanting "Journalism is not a crime!" and demanding the dismissal of the country's Interior Minister Magdy Abdel-Ghaffar.
The union was to hold a general assembly later on Wednesday.
The developments are the latest in a crisis facing Egypt's President Abdel-Fattah el Sisi who is being accused by critics of orchestrating the clampdown on the press.
Similar blockades at the union headquarters have been imposed intermittently since April 25, when security forces carried out sweeping arrests of hundreds of activists to stifle demonstrations against on the two islands.
"We are here today to defend journalism," said Yahia Kalash, the head of journalists' union who was at the rally on Wednesday. "We are defending the rights and the dignity of journalists."
Meanwhile, el Sisi's supporters gathered outside the police cordon around the union headquarters. Some chanted "El Sisi, we love you" and "Journalists are thugs," while others sing songs in support of the president. No violence was reported.
Since the deposing of Egypt's first elected President Mohammed Morsi in 2013, the government of army-chief-turned-president el Sisi has clamped down on political demonstrations, mainly by opponents demanding Morsi's return.
Thousands of protesters have been killed and detained over the past three years and a draconian anti-protest law has virtually banned all street demonstrations without prior police permit. On Wednesday, the privately owned al Maqaal daily carried a cartoon depicting riot police beating up a young man holding up a newspaper as a shield.
The two journalists were arrested on Sunday over allegations they called for anti-government protests over el Sisi's controversial decision to transfer two Red Sea islands to Saudi Arabia. Egypt's prosecutor general has since defended the raid and imposed media gag order on the investigation.
Saudi and Egyptian officials say the islands belong to the kingdom across the Red Sea and were only under Egyptian control because Riyadh had asked Cairo in 1950 to protect them.