Protests have continued for a second day in Egypt as activists announced a week-long sit-in in Cairo's Tahrir Square.
The demonstrations, which were sparked by Egyptian president Mohamed Morsi's decision to grant himself controversial new powers that would put him above the judiciary, started up again on Saturday, though with only a few hundred protesters. Minor clashes broke out when demonstrators on Mohamed Mahmoud Street near Tahrir Square threw rocks at security forces, who fired back with tear gas.
Insisting upon the need to root out what he called "weevils eating away at the nation of Egypt", Mohamed Morsi said on Friday: "I don't like, want or need to resort to exceptional measures, but I will if I see that my people, nation and the revolution of Egypt are in danger".
Morsi - who has been buoyed by accolades recently for mediating a truce between Hamas and Israel - had ordered on Thursday that an assembly dominated by the Muslim Brotherhood 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 practises.
His announcement led to clashes in several cities between supporters and opponents of Egypt's president, a clear show of the deepening polarisation plaguing the country.
One hundred wounded
In the largest rally on Friday, thousands of chanting protesters packed Cairo's Tahrir Square, the heart of the 2011 revolution, demanding Morsi quit and accusing him of launching a "coup".
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 the protesters are "calling for the fall of the regime - the are calling for the fall of the [Muslim] Brotherhood".
"The slogans coming out of Tahrir are the same that were chanted during the revolution," she reports. "Only the name of the president has changed."
Among the protesters was Mohamed ElBaradei, the former head of the International Atomic Energy Agency. On Thursday, ElBaradei - who also participated in the 2011 protests - tweeted that Morsi had "appointed himself Egypt's new pharaoh".
A number of people camped out overnight in the square in what they say will be a one-week sit-in, and a major demonstration is scheduled for Tuesday.
Protesters like Ahmed Moamen say they feel betrayed by Morsi. "I am not happy with actions of the Muslim Brotherhood and of Morsi," he told the Associated Press. "I am one of the people who voted for Morsi, but I am disappointed in him."
In Alexandria, Port Said and Suez, protests turned violent.
At least 100 people were wounded in clashes between supporters and opponents of the president.
The headquarters of Morsi's Freedom and Justice Party headquarters in Alexandria was set on fire by protesters on Friday afternoon.
The party's offices have been attacked in five cities in total.
'We are all together'
Hundreds of Morsi's supporters rallied outside the presidential palace in Cairo on Friday to express support for him.
In his speech, Morsi said: "I will never be against any Egyptians because we are all together and we need to give momentum to freedom and democracy and the transfer.
"I like to support what you want - to have stability and safety, the safety of the individual and safety of the nation."
He said he aimed to bring social and economic stability to Egypt. Doing so, he said, requires "getting rid of the obstacles of the past".
"My decision is to keep and to maintain and to preserve the nation and the people," Morsi said.
"I don't want to have all the powers...but if I see my nation in danger, I will do and I will act. I must."
Morsi, whose roots are in the Muslim Brotherhood, has also given himself sweeping powers that allowed him to sack the unpopular prosecutor general and opened the door for a retrial for Mubarak and his aides.
The president's decree aimed to end the logjam and push Egypt, the Arab world's most populous nation, more quickly on its democratic path, the presidential spokesman said.
"President Morsi said we must go out of the bottleneck without breaking the bottle," Yasser Ali told Reuters.
Al Jazeera's Hoda Abdel-Hamid said many of Morsi's supporters had been "bussed in from different parts of the country", adding that the crowd protesting Morsi's decree were angered by his speech.
"President Morsi appeared today, he said that he was speaking to all Egyptians...but he spoke on a stage to his own constituency in front of the presidential palace," said Abdel-Hamid.
"Many people here will tell you that if he's a president to all Egyptians, he should have spoke to the nation from his own office, but certainly not to his constituency."
Morsi's decree raises very serious human rights concerns, a spokesperson for the UN Human Rights Commissioner Navi Pillay said on Friday.
"We are very concerned about the possible huge ramifications of this declaration on human rights and the rule of law in Egypt," Rupert Colville said at the UN in Geneva.
"We also fear this could lead to a very volatile situation over the next few days."
Hassan Nafaa, professor of political science at Cairo University, told Al Jazeera that Morsi "is erecting himself as an absolute monarch" because he did not consult the opposition on the decision.
"The problem is not about the content of the decisions itself, but about the way it was taken," he said.
"This is a dangerous situation for the whole country. It is very confusing, because we don't know if we are in the presence of a constitutional declaration, or of a law, or of just administrative decrees," said Nafaa.
"We have all of this together in the same statement."
US State Department spokeswoman Victoria Nuland said Morsi's actions raise "concerns" for many Egyptians and the international community, and said the US urged "all Egyptians to resolve their differences over these important issues peacefully and through democratic dialogue".