Egyptian police arrested 37 people at protests around the country on Friday, describing them as members of the now-banned Muslim Brotherhood.
They were arrested following Friday prayers in Cairo, Giza, Alexandria, Fayoum, Sharqiya and Port Said, the interior ministry said in a statement on its official Facebook page.
The National Alliance to Support Legitimacy, a group led by the Brotherhood which supports ousted Islamist president Mohamed Morsi, had called for protests on Friday and throughout next week in support of "the completion of revolutionary goals and retribution for the martyrs."
Since Morsi's ouster last year, thousands of his supporters have been arrested. Hundreds of protesters were also killed when police forcibly dispersed large pro-Morsi sit-ins last year.
Pro-Morsi protests continued, however, although in diminished numbers.
In November of last year the Egyptian government passed a law that bans protesting without seeking prior permission from the security forces.
Hundreds of protesters, including Islamists and non-Islamists, have been arrested under its provisions.
A group of activists recently launched a hunger strike campaign calling for the law to be amended.