The Black Bloc, a new Egyptian anarchist group, made its first appearance last week, on the eve of the second anniversary of the 25 January 2011 revolution. With a declared aim of fighting the Muslim Brotherhood, it has drawn a lot of mainstream criticism.
The group appears to be drawing inspiration from European Black Bloc protesters, using the same tactics first seen in Germany in the 1970s and more recently at anti-globalization protests.
Internationally, Black Bloc members dress all in black, concealing their faces and often resort to violence.
The size of Black Bloc in Egypt is not clear, but the group appears to have forged links with other Egyptian revolutionary groups, including the "Ultras", who are hardcore fans of Cairo's al-Ahly football club.
Members of the group appeared in Tahrir Square on 25 January, banging drums and saying they would "continue the revolution" and "defend protesters". Others were reported by the al-Ahram news website to be blocking tram tracks in the northern city of Alexandria.
'Bringing down tyrants'
Facebook pages have been set up, attracting thousands of subscribers. They feature violent rhetoric against the Muslim Brotherhood and instructional videos on street fighting.
The Black Bloc describes itself as a group that is "striving to liberate people, end corruption and bring down tyrants".