Nobel Peace Prize winner Mohamed ElBaradei's appeal appeared to be aimed at responding to a sharp warning by the head of the armed forces a day earlier that Egypt could collapse unless the country's feuding political factions reconcile.
Two more protesters were killed on Wednesday when they were hit with birdshot during clashes with police near Cairo's Tahrir Square, a security official said, speaking on condition of anonymity because he was not authorized to talk to the press.
So far the opposition National Salvation Front headed by ElBaradei and the government of President Mohammed Morsi have been at loggerheads, with the front demanding Morsi make major concessions as a condition for any dialogue. Morsi has ignored their demands, holding his own "national dialogue" program, mainly with his own Islamist allies.
Meanwhile, violence has spiraled after first erupting in Cairo on eve of last Friday's second anniversary of the uprising that toppled authoritarian president Hosni Mubarak. It since spread around the country, with the worst violence in the Suez Canal city of Port Said, which has virtually declared itself in revolt against Morsi's government.
In response, Morsi declared a 30-day state of emergency and night curfew in Port Said and two other Canal cities, Suez and Ismailiya, and their surrounding provinces. But every night since it went into effect, tens of thousands of residents in the city have defied the curfew with nighttime rallies and marches, chanting against Morsi and the Musllim Brotherhood, which forms the backbone of his rule.
In a Tweet, ElBaradei called for an immediate meeting between Morsi, the defense and interior ministers, the Brotherhood's political party, the National Salvation Front and parties of the ultraconservative Salafi movement "to take urgent steps to stop the violence and start a serious dialogue."
He said stopping the violence is the priority, but stuck by the front's previous conditions for holding a dialogue—that Morsi form a national unity government and form a commission to amend contentious articles of the Islamist-backed constitution.
There was no immediate response from the presidency or the Muslim Brotherhood on ElBaradei's new call. Morsi was on a brief visit to Germany and was expected back in Egypt later Wednesdsay.
Over the past week, Morsi ignored ElBaradei's demands, and the Brotherhood said they don't accept conditions for talks.
The Front has depicted the unrest as a backlash against Islamists' insistence on monopolizing power and as evidence that the Brotherhood and its allies are unable to manage the country on their own.
Morsi has been holding his own national dialogue program for more than a month, touting it as a chance for non-Islamists to make their voice heard in decision-making. But almost all opposition groups have shunned it as mere window dressing.
Officials in the presidency and the Brotherhood have blamed the opposition for instigating the violence, accusing them of trying to bring down Morsi, Egypt's first freely elected president.
Late Tuesday, Morsi authorized governors of the three provinces to either cancel or limit curfew hours in an attempt to assuage public anger. Suez Governor Gen. Samer Aglan said that he will ease up the curfew while deploying more troops to the streets after midnight.