At least 11 people have been killed in Cairo in an attack on a protest near the Egyptian Ministry of Defence.
Officials say the unknown attackers used rocks, clubs, firebombs and shotguns.
Meanwhile, two leading presidential candidates have suspended campaigning in protest at the way authorities handled it the attacks.
In addition, the Freedom and Justice Party and the Salafist Nour party, which together control 70 per cent of the seats in parliament, decided to boycott a meeting with the ruling Supreme Council of Armed Forces.
Reports indicate that many of the protesters who were attacked outside the defence ministry building were supporters of a Salafist preacher barred from standing in the election.
The first round of the presidential election is just three weeks away.