Dozens of women have held a vigil outside Egypt's presidential palace, calling for the release of thousands detained for violating the country's controversial protest law.

The protest law, in place since 2013, criminalizes any gathering of more than five people without prior police permission.

The vigil Sunday outside the palace of President Abdel-Fatah el-Sissi didn't seek prior permission but ended peacefully. It comes a year after 23 secular activists, including a prominent rights defender, were arrested there for protesting against the law. They currently are serving a two-year sentence.

Police formed a cordon around the women, who raised photos of detainees. Some protesters raised banners that read: "Ramadan is not the same without you," in reference to the Muslim holy month of fasting that brings families together.