CAIRO — The spokesman for Egypt’s Interior Ministry on Saturday said a bomb went off next to a police institute in eastern Cairo, but caused no casualties.

The blast came the morning after a series of bombings targeted police across Cairo, leaving six dead and sparking fears of an intensification of violence following the ouster of Islamist president Mohammed Morsi in a military coup on July 3.

Gen. Hani Abdel-Latif told The Associated Press that the blast took place at 7 am on Saturday in the busy district of Ein Shams, but damaged only the institute’s walls.

The bombing came as Egypt marks the 3rd anniversary of the 2011 uprising that toppled longtime autocratic president Hosni Mubarak. Morsi supporters as well as military loyalists plan rival rallies.

Friday’s attacks fueled fears of an increasing militant insurgency in retaliation for the military’s ouster last year of Morsi and the subsequent crackdown on his Muslim Brotherhood and other Islamists. Hours after the bombings, angry residents joined security forces in clashes with Brotherhood supporters.

On Saturday, supporters and opponents of the ousted Islamist president were set to hold 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.

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.”