CAIRO - Anger between Egypt's rival political camps erupted into street battles Wednesday after Islamist supporters of President Mohammed Morsi tore down tents belonging to antigovernment demonstrators, raising the possibility of widening violence over the nation's proposed constitution.

Pro-Morsi factions overran about 200 protesters camped outside the presidential palace in northern Cairo. The clashes came after the Muslim Brotherhood's Freedom and Justice Party called thousands of its members into the streets in a counterdemonstration to drive opposition movements from the palace.

Shoving and punching spilled down a boulevard as hurled stones, swinging sticks, and firebombs filled the dusk in one of Cairo's wealthiest areas.

More than 200 people were injured across a cityscape that had the charged air of a fluorescent-lit battlefield. Media reported clashes spread to other cities, including attacks on several Muslim Brotherhood offices. There were reports of at least three deaths.

Police were slow to react in Cairo but eventually arrived and tried to separate the two sides even as the skirmishes raised fears that animosity between Islamists and the mainly secular opposition was a dangerous foreshadowing.

The clashes revealed new cracks in Morsi's government from officials disturbed by the meddling of the Brotherhood. Three presidential advisers quit, including Seif Abdel-Fattah, who told media: "We can no longer stay silent, because they [the Brotherhood] have harmed the nation and the revolution."

The defections further marred the credibility of Morsi's administration at a time when Egypt's political polarization and continuing unrest have alarmed the international community.

Tensions began two weeks ago when Morsi, a former Brotherhood leader, issued a decree that expanded his powers and protected the Islamist-dominated constitutional assembly from judicial oversight.

Opposition factions drew tens of thousands who marched on the palace Tuesday to protest Morsi's authority and the charter, which they say would open the country to Islamic law and a scaling back of civil rights. The demonstration angered the Brotherhood, which on Saturday avoided confrontation by a holding a huge rally miles away from Tahrir Square, where anti-Morsi movements have made their base.

The Brotherhood was more aggressive Wednesday. The violence was reminiscent of street fights in 2011, when loyalists to Hosni Mubarak attacked peaceful demonstrators in Tahrir Square. The Brotherhood and Morsi fought against Mubarak forces, but they are now likened to the authoritarianism of the regime they replaced.