Supporters and opponents of Egypt's president have clashed in several cities after he assumed sweeping new powers, a clear show of the deepening polarisation plaguing the country.

In the largest rally on Friday, thousands of chanting protesters packed Cairo's Tahrir Square, the heart of the 2011 revolution, demanding Mohamed Morsi quit and accusing him of launching a "coup".

Buoyed by accolades from around the world for mediating a truce between Hamas and Israel, Morsi on Thursday issued a declaration giving himself powers that go beyond those held by toppled president Hosni Mubarak, putting himself above the judiciary.

He also ordered that an Islamist-dominated assembly writing the new constitution could not be dissolved by legal challenges.

Liberal and secular members earlier walked out of the body, charging it would impose strict Islamic practices.

"I am for all Egyptians. I will not be biased against any son of Egypt," Morsi said on a stage outside the presidential palace on Friday, adding that he was working for social and economic stability and the rotation of power.

Thousands of protesters gathered in Tahrir Square after  opposition leaders called for a "million-man march" to protest against what they say is a coup by Morsi. 

 

Al Jazeera Hoda Abdel-Hamid, reporting from Cairo, said that while the crowds had thinned slightly, there were still many people in Tahrir Square, "calling for the fall of the regime - the are calling for the fall of the [Muslim] Brotherhood".

Protests also turned violent in Alexandria, Port Said and Suez.