Thousands of people packed Cairo's Tahrir Square on Friday, with Islamist groups dominating the protest meant to show unity during a fragile transition from ousted president Hosni Mubarak's regime.
The rally was officially to start after the Muslim noon prayer but thousands had already made their way to the square overnight and by morning chants calling for an "Islamic state" rang across Tahrir.
The powerful Muslim Brotherhood, in coordination with other fundamentalist Muslim groups, had called for the demonstration, sparking fears of tensions with secular groups already camped out in Tahrir Square since July 8.
But after two days of meetings, secular and Islamist groups agreed to put their differences aside and focus on the common goals in order to save the revolution that toppled Mubarak in February, organisers said.
At least 15 parties and political movements are participating in Friday's protest.
Among the key demands are the end to military trials of civilians, the prosecution of former regime members found guilty of abuse, and the redistribution of wealth.
Since July 8, mainly secular protesters have been camped out in Tahrir Square -- the epicentre of protests that toppled Mubarak-- to denounce the ruling military council over the slow pace of reform.
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The military has also come under fire for alleged rights abuses and for using Mubarak-era tactics to stifle dissent.
But Islamist groups had for the most part stayed away from the sit-in.
Last week, Islamist groups held their own demonstration and accused the Tahrir protesters of going against what they say is the country's "Islamic identity."
The Supreme Council of the Armed Forces (SCAF) -- which took power when Mubarak stepped down-- has recently accused Tahrir protesters of "sowing instability" and "driving a wedge between the army and the people," singling out the secular April 6 movement as the main culprit.
Last week, Field Marshal Hussein Tantawi, the head of SCAF and Mubarak's long-time defence minister, pledged in a television address to work for a free system through fair elections and a constitution.
Parliamentary elections have been announced for autumn, to be followed by the drafting of a new constitution and then a presidential election.
Nationwide debates had raged for weeks over whether to hold elections first or draft the charter first.
Secular groups feared that an early election would benefit the well-entrenched Muslim Brotherhood, which would then have too much influence in drawing up the new constitution.