A police station was set on fire in Cairo and more than 180 protesters arrested when heavy clashes erupted between supporters of ousted President Mohammad Mursi and security forces, the interior ministry said.
Mursi’s supporters, who took to the streets after Friday prayers, defied a new protest law banning protests without a prior police permit.
Police used tear gas against protesters in the capital’s Mohandessin district and on a key road leading to the pyramids, Agence France-Presse reported.
Protesters responded by throwing stones and burning tyres, security officials said. Police dispersed protests also in the cities of Alexandria, Suez, Mahalla and Qena.
A police station in the Giza’s Talebiya area was set on fire, the Daily Youm7 reported, showing a video of the building in flames.
Footage showed a protester throwing documents into a large fire outside of the building.
Since Mursi’s ouster, his supporters have held almost daily rallies across the country demanding his reinstatement.
One student was killed and 21 injured in clashes that took place between Muslim Brotherhood supporters and official security forces around the University of Cairo on Thursday, the Health Ministry said.
The Interior Ministry had warned against unauthorized demonstrations under a new protest law recently.
The Muslim Brotherhood said they would not respect the law and would continue with their protests without seeking to obtain police permits.
Requesting a police permit would amount to a de-facto recognition of the authorities, which the Islamist group rejects as illegitimate.
Friday protests were called for to mark 100 days since the killings of a number of prisoners at Abu Zaabal prison in northern Egypt.
The alliance has called for nationwide protests on Saturday morning to show support for a group of girls who were handed heavy jail terms this week for participating in an anti-government protest.
The girls, between 14 and 21 years of age, were part of a group called “7am” which stages demonstrations early in the morning, before heading to schools.
Amnesty International called for the immediate and unconditional release of the detained females, reported AFP.