The Egyptian constitution - which could pave the way for army chief General Abdel Fattah al-Sisi to announce his candidacy for president - was approved by 98.1% of voters, according to the Electoral Commission.
Egyptian voters have overwhelmingly approved a new constitution, an Interior Ministry official has said citing preliminary results.
This could pave the way for army chief General Abdel Fattah al-Sisi to announce his candidacy for president.
"Turnout so far may exceed 55 percent and the approval of the constitution is perhaps more than 95 percent," Major General Abdel Fattah Othman told satellite channel Al-Hayat.
He was citing preliminary results of the two-day referendum.
At least five people were killed in confrontations between Muslim Brotherhood supporters and police in Egypt, according to official sources.
The bloodiest clashes were in Sohag, south of Cairo, where there were reports that four people had been killed and others wounded, but conflicting accounts of what happened.
The Interior Ministry alleges that Muslim Brotherhood supporters opened fire on a crowd near a polling station, but local officials said it was the supporters who had been killed.
A small bomb also went off in Cairo, but no-one was injured.
One man was killed in clashes between security forces and supporters of ousted President Mohamed Morsi's Muslim Brotherhood on the first day of a constitutional referendum, security sources said.
Mahmoud Sayed Gomaa, 25, was killed during a protest against the referendum near a polling station in the province of Bani Suef, south of Cairo.
The referendum is the first ballot since the military overthrew Morsi on July 3 after mass protests against his rule.
Egyptians queued at polling stations across the country amid a heavy security presence as today's constitutional referendum got under way.
Several witnesses in Giza, near Cairo, have reported and tweeted photos of an explosion, believed to be a bomb, that went off outside a courthouse ahead of today's constitutional referendum.
There are no reports of injuries.
The bombed courthouse in Imbaba. Front of the building damaged, windows blown out. http://t.co/sIVRhTrHTt
Clean up began: Governor Giza tells me not sure who is behind it but the court will be up and running by end of day http://t.co/44qfslNO7c
160,000 soldiers and 200,000 policemen are due to deploy across Egypt to guard polling stations and voters in Egypt today as the country votes on a draft of their new constitution.
Polls in Egypt will open later in the latest milestone in the army-backed government's political roadmap.
Deposed President Morsi's Muslim Brotherhood have called for a boycott of the vote. They see army chief General al-Sisias the mastermind of the coup which seen the country's first democratically elected leader forced out, and the country reduced to a "police state."
Egyptians will vote later today in a constitutional referendum, the first ballot since the military overthrew Islamist president Mohamed Morsi, the country's first freely elected head of state.
It is expected the ballot will lead to a presidential bid by army chief General Adbel Fattah al-Sisi.
It is expected that Egyptians will turn out in big numbers and vote "yes" in the two-day referendum.