Leftist presidential candidate Khaled Ali arrived at the ministry of defence sit-in in a show of solidarity with the protesters after they were attacked by thugs and locals in Abbasiya Square in the early hours of Wednesday morning.
"As long as the Supreme Council of the Armed Forces [SCAF] is still in power the massacres and clashes will continue to take place," Ali told Al-Ahram Arabic portal, adding that all the presidential candidates should unite and force SCAF to step down.
Earlier Ali had announced that he suspended his campaign in protest over the clashes in Abbasiya, which have left at least eleven dead.
Presidential candidate Hamdeen Sabbahi announced he will lead a march to the sit-it this afternoon from Al-Fateh Mosque, which should have started gathering at 5:00pm.
Central Security Forces (CSF) commanders ordered CSF vehicles to evacuate the area where clashes took place after protesters threatened to torch the vehicles.
Protesters at the site say they have bitter memories of similar CSF vehicles attacking citizens at the "Friday of Rage," demonstrations on 28 January, 2011 - the first day the police attacked protesters in Egypt's nascent revolution.