((Writethru w/ new lede/toll, grafs 2-3, 6-7, headline)
Violence erupted across Egypt Friday leaving at least seven people dead, as protesters marked the second anniversary of the uprising that ousted former president Hosni Mubarak. The government-controlled news agency MENA reports more than 450 people were injured in the violence.
A health ministry spokesman said six of the fatalities occurred in the city of Suez, where protesters with rocks and bottles battled heavily armed security forces, before government troops took up positions in the city early Saturday. A seventh victim died in Ismalia.
In Cairo, street battles between stone-throwing protesters and riot police firing tear gas erupted early in the day Friday in Tahrir Square and continued for hours near Interior Ministry headquarters, state television facilities and the presidential palace. Rioting was also reported in Alexandria, Port Said, Mahalla and Ismalia.
The secular-leaning political opposition called Friday's protests against President Mohamed Morsi and his Islamist Muslim Brotherhood allies. Opposition leader Mohamed ElBaradei sent a message on Twitter calling on protesters to "finally achieve the objectives of the  revolution."
The Muslim Brotherhood, eyeing parliamentary elections likely to begin in April, urged its supporters to stay away from the protests and marked the anniversary with a national charity drive.
Critics say the country's new Morsi-backed constitution -- drafted without opposition input and approved in a hastily organized referendum in December -- fails to provide adequate human rights protections and fails to curb the power of the military establishment.
Mr. Morsi's supporters argue that enacting the constitution quickly was crucial to restoring the political stability needed for economic recovery.