The two-day balloting is a heavy blow to the Muslim Brotherhood's campaign for the reinstatement of Morsi and paves the way for a likely presidential run by the nation's top general, Abdel-Fattah al-Sissi.

A massive security operation was underway to protect polling stations and voters against possible attacks by militants, with 160,000 soldiers and more than 200,000 policemen deployed across the nation of some 90 million people.

Shortly before polls opened, an explosive device went off outside a Cairo courthouse in the densely populated neighborhood of Imbaba. The blast damaged the front of the building but caused no casualties.

Long lines of voters began to form nearly two hours before polling stations opened in Cairo, including in Imbaba, where the blast promptly whipped up anti-Brotherhood sentiment with chants and shouting against the political group.

The Tuesday and Wednesday balloting is the first electoral test for the popularly-backed coup that ousted Morsi and his Brotherhood.

Morsi's Brotherhood, which is now branded as a terrorist group the military-backed interim government, has called for a boycott of the vote. Morsi himself is facing three separate trials on charges that carry the death penalty.

NTJ/BA