At least one person was killed and more than 650 wounded in clashes between riot police and protesters in Cairo's Tahrir square Saturday, official said, after a protest demanding the ruling military transfer power swiftly to a civilian government.
Protests also erupted in other cities, including Alexandria and Suez, witnesses said.
Egypt holds its first parliamentary election, from November 28, since president Hosni Mubarak was toppled in a popular uprising in February and parties and the ruling military are jostling for position.
Police pulled down the tents of about 100 protesters who had camped in the square overnight after a demonstration Friday of about 50,000 people, mostly Islamists, against the military leadership.
That prompted around 5,000 protesters to return to the square and clashes erupted. Police fired rubber bullets and buildings and two cars in the square were set on fire, witnesses said. A third vehicle, close to the Arab League's headquarters, was also on fire.
The people want to topple the regime! hundreds of youths chanted as they rushed towards a line of police.
State news agency MENA cited the health ministry's spokesman as saying 676 people had been hurt and Ahmed Mahmoud, a 23-year-old demonstrator, died in hospital after being shot.
Riot police, who used tear gas to clear the area in the early evening, later fired more tear gas at protesters who had regained control of the square, witnesses said. Police beat protesters with batons while protesters broke off chunks of cement from sidewalks to throw at the police.
We are fighting them non-stop, shouted one protester.
Egyptian state television said Prime Minister Essam Sharaf called on protesters in Tahrir to clear the square.
The Muslim Brotherhood's Freedom and Justice Party said it denounced the break-up of the Tahrir sit-in by force. (This is) reminiscent of the practices of the defunct regime's Interior Ministry.
The April 6th Youth Movement said it opposed the use of force against peaceful protesters and demanded the interior minister quit.
The demonstrators denounced Field Marshal Mohamed Hussein Tantawi, the head of Egypt's ruling military council, while some criticised the Muslim Brotherhood, whom they accused of working to further their own political ends.
We are not political parties and we hate the Brotherhood who gave up on the revolution and the people, Medhat Fawzy said. We are Egyptian youth, he added, flashing victory signs and chanting down down Tantawi.
In the northern port city of Alexandria demonstrators chanted against the military council: This is their understanding of change, they beat our brothers in Tahrir!
In the eastern city of Suez, protesters tore down banners of members of Mubarak's disbanded National Democratic Party who are running in the election.
State television said 40 of the wounded were police officers and said 18 troublemakers had been arrested.
Friday's rally appeared to be the biggest Islamist challenge to military rule since the largely secular uprising that toppled Mubarak. The demonstration was mostly comprised of Brotherhood members and their harder-line Salafi rivals.
Protesters expressed anger at a draft constitution that Deputy Prime Minister Ali al-Silmi showed to political groups earlier this month which would give the army exclusive authority over its internal affairs and budget.
The election could be disrupted if parties and the government fail to resolve the row over the draft constitution that had denied parliamentary oversight of the army, potentially allowing it to defy an elected government.
As clashes raged in Tahrir square, al-Silmi and the Brotherhood appeared to be negotiating, through press statements and the state news agency, on percentages of members of parliament (MPs) needed to approve the assembly that will write the constitution.
MENA reported that al-Silmi had amended some clauses of the constitutional proposal, including one to say Egypt is a democratic state instead of democratic civil state, a move likely to anger liberals who fear that a parliamentary majority could seek to turn Egypt into an Islamic state.
Al-Silmi said the committee chosen to write the constitution would not be confined to the larger groups in parliament to ensure a constitution that reflects national consensus and receives the consent of all segments of society.
Political analyst Ezzedine Fishere said he did not expect the amendments to appease Islamist groups.
(Islamists) see that they will get a majority in parliament and hence want total freedom in choosing the constitutional committee and writing the constitution, he said.
Analysts say Islamists could win 40 percent of parliament seats, with a big portion going to the Brotherhood.
What is happening now is a showdown between the two factions ... an on-the-ground confrontation with each party trying to enforce its will, the military council from one end and the Islamist currents from the other, Fishere said.
MENA reported that al-Silmi had amended the constitutional proposal to say members of the constituent assembly writing the constitution would be chosen by a majority of elected MPs instead of his earlier announcement that they would be chosen by a two-thirds majority.
(Reporting by Shaimaa Fayed, Marwa Awad, Omar Fahmy, Patrick Werr, Tamim Elyan and Abdel Rahman Youssef; Editing by Janet Lawrence)