Five months after president Hosni Mubarak's ouster, Egyptians are being called to return to the streets for new mass protests amid frustration over the handling of a promised transition to democracy.
Hailed as heroes for not having sided with Mubarak during the January-February uprising, Egypt's ruling military council has increasingly become the target of protesters' anger.
Pro-democracy activists have expressed their fury over continued military trials of civilians.
They say police officials responsible for repression before and during the revolt are still showing up for work.
And some take issue with the military's timetable for elections and the drafting of a new constitution.
"We want real cleansing, real trials, real government," said the Coalition of Revolution Youth, a grouping of pro-democracy movements that helped launch the anti-Mubarak revolt.
"I want to see real change," said Mustafa Shawki, one of the coalition members in a video posted on their Facebook page. "We must be clear, politics is not for the army."
Another Facebook group "We are all Khaled Said" -- named after a man who died after being beaten by police last year and has become a symbol of the fight against police brutality -- insisted that "this country must change."
The group, which has nearly 1.5 million members, said "those found guilty of corruption must be brought to justice."
The National Association for Change, founded around leading dissident and former UN nuclear watchdog chief Mohamed ElBaradei, called for an end to "the repressive methods of the old regime."
Rallies are planned across Egypt on Friday, including in Cairo's Tahrir Square -- the epicentre of the protests which led to Mubarak being toppled on February 11.
The powerful Muslim Brotherhood said on Wednesday it would take part in the protests after initially announcing it was staying away.
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"The Brotherhood has decided to participate in the demonstration on July 8 (aimed at) raising the flag of justice so that all rights can be regained, and all criminals punished and all the demands of the revolution met," it said.
The Brotherhood initially disassociated itself from the demonstration because one of the rally's earlier demands was to call for a new constitution before legislative elections in September.
The military council has set parliamentary elections for September, but some fear early polls will benefit the long well-organised Muslim Brotherhood.
Others have called for a new constitution before elections, so as not to give the Islamist group too much influence in drafting the charter.
The military council's number two, General Sami Enan, has vowed the elections will be "free and fair".
Islamic fundamentalist Salafi groups also said they would join Friday's protest, listing the same demands as the secular pro-democracy groups.
The protest comes amid heightened tensions, almost five months since Mubarak's fall following three decades of autocratic rule.
Egypt stocks fell on Wednesday after a series of clashes and ahead of the rally. The main EGX-30 index closed down 2.17 percent at 5,320.54 points.
Earlier, hundreds of people torched police cars and tried to storm government buildings in the city of Suez, after a court confirmed the bail of police accused of murdering protesters.
The protesters, including families of victims who died in the protests which ousted Mubarak, were furious when a court rejected the public prosecutor's appeal against a decision to free the police officers on bail.
Routine police torture and abuse during the Mubarak era were a driving force behind the popular uprising.
Last week, violent clashes erupted around Cairo, culminating in a confrontation in Tahrir Square between the police and around 4,000 protesters, among them families of some of those who died in anti-regime protests.
The Supreme Council of the Armed Forces -- led by Mubarak-era defence minister Field Marshal Hussein Tantawi -- has sought to calm the situation by announcing the creation of a fund to assist victims' families.
Officials say 850 people died in the January-February uprising, and at least 6,000 people were injured.
The rising number of military trials -- up from 7,000 to 10,000 since February, according to local and international human rights groups -- has further enraged pro-democracy activists, who demand an end to such trials for civilians.