Egyptians are to vote Saturday in the first round of a referendum on a disputed draft constitution that has sparked protests, DPA reported.
President Mohammed Morsi's Muslim Brotherhood and Islamist allies have campaigned for approving the charter, saying it is necessary to fast-track the transition from the authoritarian rule of president Hosny Mubarak, who was forced to step down almost two years ago.
The opposition says the constitution, drafted by an Islamist-led constituent assembly, could undermine women's and political rights, and sideline minorities.
Critics also say the charter is heavily influenced by Islamists.
The main opposition coalition, the National Salvation Front, has urged a "No" vote.
State media reported that thousands of army and security personnel would be deployed outside polling stations to keep order.
An electoral commission in charge of the process had to spread polling across two days after many judges refused to oversee the balloting in protest at perceived curbs on freedoms in the draft constitution.
Without judicial supervision, polling will be illegal.
About 25.8 million Egyptians are eligible to vote in the first round of the polls in 10 provinces and cities including Cairo, according to government figures.
Polls are to open at 8 am (0600 GMT) and close at 7 pm (1700 GMT).
The second and final stage of the vote is to be held a week later in the country's 17 other provinces.
The final result is to be determined by the majority of the valid ballots cast in both rounds, according to the electoral commission.
No date has been set yet for announcing the result.
If the draft constitution is voted down, Morsi will call an election within three months to pick a new constituent assembly.