Supporters and opponents of ousted Islamist president Mohamed Morsi are set to demonstrate Saturday on the third anniversary of Egypt's uprising marked by tensions a day after bombings hit Cairo.
Both Morsi's backers and those of the military, which ousted him in July, have called for mass protests, prompting security forces to block off areas of the capital over fears of more violence.
Tahrir Square, epicentre of the popular revolt that toppled autocratic president Hosni Mubarak in 2011, was closed off by police and soldiers ahead of the commemoration.
Mubarak was forced to step down on February 11, 2011 after 18 days of demonstrations that left some 850 people dead, ending his 30-year hold on the Arab world's most populous country.
Immediately after the ageing president's ouster, Egypt's powerful armed forces took power, handing the reins over 16 months later to Morsi -- the country's first democratically elected, civilian head of state.
But late last June, after just one year of turbulent rule by Morsi's Freedom and Justice Party, millions of Egyptians took to the streets to demand his resignation.
Three days later, army chief General Abdel Fattah al-Sisi announced Morsi's ouster. Since July, the Islamist president has been held by the military and is on trial in four separate cases.
Since then, security forces have embarked on a bloody crackdown on Morsi's supporters -- particularly his Muslim Brotherhood, which dominated all major polls after the 2011 uprising.
At least 1,000 people have been killed and thousands of Islamists have been arrested, while the military-installed authorities branded the Brotherhood a "terrorist" organisation in December following a deadly attack on the police.
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But the Brotherhood issued a condemnation of the attack, and an Al-Qaeda-inspired jihadist group claimed the bombing.
Attacks against security forces have been on the rise since Morsi's ouster, with the jihadist groups behind the violence saying they are avenging the "massacre" of the Islamist leader's supporters.
And on Friday, the police were targeted once again when four blasts, including a car bomb, hit its installations and men in the city, killing six people.
After each blast, residents of the areas targeted took to the streets, brandishing posters of Sisi, shouting praise for the authorities and denouncing the Brotherhood.
The army's political comeback in Egypt signalled a return to the former regime's authoritarianism for some of the activists who led the January 25 revolution.
But for the millions who took to the street to demand Morsi's ouster last year, the interim authorities and the "democratic transition" they have announced represent a modicum of stability after three years of unrest.
Interim interior minister Mohamed Ibrahim has called for demonstrations from Friday in support of the government and to counter what he said was an Islamist "plot to spark chaos".
Ibrahim also vowed security forces would respond with "firmness" to any attempt by the "Muslim Brothers to sabotage the ceremonies".
Officials in the government and military have been hinting for days that the turnout at the pro-government rallies on Saturday could be a bellwether for a run by Sisi in this year's presidential elections.
But Morsi's Islamist backers have are calling for 18 days of protests, after 14 of their supporters were killed in clashes with police and rival protesters on the margins of their marches.
Amnesty International has denounced "state violence on an unprecedented scale over the last seven months".
It added that "three years on, the demands of the '25 January Revolution' for dignity and human rights seem further away than ever".