Egypt’s opposition has called for an investigation into allegations of vote fraud in the referendum on an Islamist-backed constitution.
The Muslim Brotherhood, the main group backing the charter, claimed it passed with a 64 per cent “yes” vote.
Official results have not been released yet and are expected today.
If the unofficial numbers are confirmed, it will be a victory for Islamist President Mohammed Morsi.
The allegations look likely to prolong the struggle that has exploded in deadly street violence at times over the past month.
“The referendum is not the end game. It is only a battle in this long struggle for the future of Egypt,” said the National Salvation Front, the main opposition group.
“We will not allow a change to the identity of Egypt or the return of the age of tyranny.”
The opposition claims the new constitution seeks to enshrine Islamic rule in Egypt and accuses the Islamists of trying to monopolise power.
Critics say it does not sufficiently protect the rights of women and minority groups and empowers Muslim clerics by giving them a say over legislation.
Some articles were also seen as tailored to get rid of Islamists’ enemies and undermine the freedom of labour unions.
The opposition front said it filed complaints to the country’s top prosecutor and the election commission asking for an investigation.
“The results of the referendum are for sure because of the rigging, violations and mismanagement that characterised it,” the opposition group said.
However, the Brotherhood insisted violations were limited and should not affect the referendum’s integrity.
The Freedom and Justice Party, the Brotherhood’s political arm, said it hoped the passage of the constitution would be an “historic opportunity” to heal Egypt’s divisions and launch a dialogue to restore stability and build state institutions.
If the violations are considered serious enough, there could be new votes in some areas that alter the results slightly.
The referendum was conducted in two stages with the first vote on December 15 and the second on Saturday. The Muslim Brotherhood and some media outlets have accurately tallied the outcome of past elections by compiling numbers released by electoral officials at thousands of individual polling stations shortly after voting closes.
Turnout for the vote was 32 per cent of Egypt’s more than 51m eligible voters, according to the Muslim Brotherhood. That was significantly lower than other elections since the uprising ended in February 2011.
The opposition has pointed to the low turnout as well as allegations of violations in the voting to cast doubt on the legitimacy of the referendum.
The Brotherhood said 64 per cent voted “yes” to the constitution in a tally of both stages of voting. For Saturday’s second stage only, the Brotherhood said 71 per cent of those who voted said “yes” with 99 per cent of polling stations accounted for.
As expected, it was a jump from the first round of voting when about 56 per cent said “yes”. The provinces that voted in the second round were known for being a base for Brotherhood supporters.
Only about 8m of the 25m Egyptians eligible to vote in the second stage – a turnout of about 30 per cent – cast their ballots.
Some 32 per cent of eligible voters participated in the first round.
The local media has reported results similar to the Brotherhood’s. State-owned Al-Ahram newspaper said in its English language online version that 16.2m eligible voters cast their vote, and the constitution passed with 63.96 per cent. Those numbers reflected totals of the two stages of voting.