CAIRO — Egyptian rights groups called Sunday for a repeat of the first round of the constitutional referendum, alleging the vote was marred by widespread violations.
Islamists who back the disputed charter claimed they were in the lead with a majority of "yes" votes, though official results have not been announced.
Representatives of seven rights groups charged that there was insufficient supervision by judges in Saturday's vote in 10 of Egypt's 27 provinces and independent monitors were prevented from witnessing vote counts.
The representatives told a news conference that they had reports of individuals falsely identifying themselves as judges, of women prevented from voting and that members of Islamist President Mohammed Morsi's Muslim Brotherhood were allowed inside polling stations.
They also complained that some polling centers closed earlier than scheduled and that Christians were denied entry to polling stations.
Mohamed ElBaradei, Egypt's best-known reform leader, was as frustrated by how the referendum was run as the rights groups.
"Is a referendum held under insufficient judicial supervision, clearly tenuous security and the violence and violations we are witnessing the road to stability or playing with the country's destiny?" Mr. ElBaradei, a Nobel Peace laureate and former U.N. nuclear agency chief, wrote on his Twitter account.
The vote is the latest stage in a nearly two-year struggle over Egypt's identity since the ouster of longtime leader Hosni Mubarak in a popular uprising.
The latest crisis over the Islamist-backed charter evolved into a fight — deadly at times — over whether Egypt should move toward a religious state under Mr. Morsi's Brotherhood and its ultraconservative Salafi allies, or one that retains secular traditions and an Islamic character.
Underlining the tension, some 120,000 army troops were deployed to help the police protect polling stations and state institutions after clashes between Mr. Morsi's supporters and opponents over the past three weeks left at least 10 people dead and about 1,000 wounded.
Potentially adding to questions over the legitimacy of the vote is the low turnout in the first round — unofficially estimated at 32 percent, which if confirmed would be far lower than the presidential or parliamentary elections following Mubarak's fall.
A second round is to be held in the remaining 17 provinces Saturday.
Those who did vote were deeply divided.
The Brotherhood claimed about 57 percent voted in favor of the draft. The state-owned Al-Ahram daily published similar unofficial results in its online edition. The Brotherhood, which has in the past accurately predicted election results, relied on vote tallies announced at individual polling stations across the country and collected by its activists.
The strongest "no" vote was in Cairo, with 68 percent, according to the official website of Egypt's state television. The only other province where the "no" vote won the majority was Gharbiyah in the Nile Delta, north of Cairo.
The "yes" vote was strongest in deeply conservative, rural provinces of the south, Assiut and Sohag. It also narrowly carried Egypt's second largest city, Alexandria, where nearly 56 percent voted "yes," according to updated results after earlier, partial data showed "no" votes ahead.
The Brotherhood and other Islamists enjoy wide support in most of the 17 provinces voting next Saturday, something that could work in favor of the "yes" vote.