(CNN) -- Backers of Egypt's Muslim Brotherhood battled police in Cairo and other cities after Friday prayers. At least three people died and 265 were arrested, the Interior Ministry said.
The ministry blamed the deaths on the Muslim Brotherhood, the Islamist group that the Egyptian government declared a terrorist organization on Wednesday.
The government has threatened to arrest anyone who attends Muslim Brotherhood protests or provide financial support to the group, which helped propel ousted President Mohamed Morsy to power.
Morsy, the nation's first democratically elected president, was forced out of office in July by the nation's military and arrested following widespread protests and petitions calling for his removal.
Detractors said he was a tyrant trying to impose conservative values. Supporters called his removal a coup and a blow to the democratic movement that toppled former Egyptian strongman Hosni Mubarak in 2011.
Since Wednesday's declarations, hundreds of Muslim Brotherhood supporters have been arrested.
EgyNews, a state-run news agency, previously reported the Interior Ministry had told police to confiscate copies of the group's newspaper and seal off the publishing house that prints it.
The unrest comes as Egyptians prepare to vote a new constitution next month.
The proposed constitution would ban religious political parties and put more power in the hands of the military.
The Muslim Brotherhood has vowed to continue protesting.
"Let's begin with full force and peacefulness a new wave of majestic anti-coup action in a 'Revolutionary Rage' week," the group said Thursday on its website.