Clashes across Egypt on Friday left at least 30 people killed as tens of thousands of supporters of ousted President Mohammed Morsi protested his removal by a popularly backed military coup.

An alliance of Islamist parties and movements, including Morsi’s Muslim Brotherhood, called for nationwide “peaceful” protests on Friday, and vowed for more in a statement released early Saturday.

Islamists are demanding the military to restore Morsi, who is the country’s first democratically elected leader.

There are at least eight provinces where clashes have been reported on Friday.

At least 12 people were killed in the Mediterranean city of Alexandria as Morsi's supporters and opponents fought a pitched street battle, the official MENA news agency said.

In the restive north of the Sinai peninsula, armed Morsi supporters stormed the provincial headquarters in the town of El-Arish after a gunfight and raised the black banner of Al-Qaeda-inspired Islamist militants, an AFP correspondent said.

In Cairo's iconic Tahrir Square, at least two people were killed when Morsi supporters traded fire with his opponents, state television reported.

But the army intervened by separating the protesters using armored vehicles.

“We are not taking sides. Our mission is to secure the lives of protesters,” military spokesman Colonel Ahmed Ali told AFP.

Four protesters were killed outside the Republican Guard headquarters after breaking away from a pro-Morsi demonstration, the official MENA news agency reported.

The bodies of two people were covered with sheets, said an AFP correspondent, adding that another protester was shot in the head.

Soldiers had warned a protester waving a picture of the ousted president not to approach their barbed wire cordon.

They opened fire when he ignored them, and shots were then heard from both sides, an AFP reporter said.

Friday's violence came as the supreme guide of Morsi's Muslim Brotherhood, Mohammed Badie, vowed that members of the Islamist movement would throng the streets in their millions until his presidency is restored.

Badie appeared at Cairo's Rabaa al-Adawiya mosque to screams of joy from jubilant supporters, following reports he had been detained after Wednesday's ouster of the president.

“Millions will remain in the squares until we carry our elected president, Mohamed Morsi, on our shoulders,” Badie told the crowd, before leading chants of “Military coup!” and “Invalid!”

(With AFP)