Clashes erupted between riot police and protesters in Cairo's Tahrir square Saturday after police dispersed a sit-in by demonstrators demanding the ruling military transfer power swiftly to a civilian government.
Around 100 protesters had camped in the square overnight after Friday's demonstration which had gathered some 50,000 people, mostly Islamists.
After police pulled down the tents, hundreds of protesters returned to the square, and clashes erupted, with police and protesters throwing stones at each other, said Reuters' witnesses.
Police fired tear gas, and a destroyed police car was seen lying in the square after witnesses said they earlier saw protesters climb into the vehicle.
The Muslim Brotherhood's Freedom and Justice Party said in a statement it denounced the breakup of the Tahrir sit-in by force.
The break-up (of the sit-in) ... led to injuries, some serious, according to some media reports, the party said.
(This is) reminiscent of the practices of the defunct regime's interior ministry.
State television reported seven policemen had been injured during the breakup of the sit-in Saturday and five troublemakers had been arrested and the legal procedures were being taken.
Men with long beards and women in veils had dominated Friday's rally that appeared to be the biggest Islamist challenge to military rule since the largely secular uprising that toppled autocratic President Hosni Mubarak in February.
Protesters expressed their anger at a constitutional draft 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.
Egypt's parliamentary elections, which will be the first since Mubarak's ouster and are intended to be the first significant step towards a civilian democratic system, are set to begin on November 28.
But the polls could be disrupted if political parties and the government fail to resolve the row over the constitutional proposal that would deny parliamentary oversight of the army, potentially allowing it to defy an elected government.
Liberal and leftist parties also marched to Tahrir for the rally but it was a largely Islamist affair with members of the Muslim Brotherhood's Freedom and Justice party and their more hardline Salafi rivals, represented by several parties.
The April 6th Youth Movement also issued a statement in which it said it opposed the use of force against peaceful protesters and demanded that the interior minister leave immediately.
(Reporting by Shaimaa Fayed; Additional reporting by Omar Fahmy; Editing by Sophie Hares)