A majority of Egyptian voters have backed a controversial charter in a two-round referendum that deeply polarised the country, ruling Islamists and official media said on Sunday.
The Muslim Brotherhood, which President Mohamed Morsi hails from, and the official Al-Ahram newspaper reported that about 64 percent voted for the charter, according to preliminary results.
Turnout over both rounds was roughly 32 percent, according to Muslim Brotherhood figures posted on its Twitter account.
The results are based on reports from returning officials from the vast majority of stations over the two rounds, which were held a week apart. The election committee will announce the final results within two days.
On the eve of Saturday's polling, clashes in Egypt's second city Alexandria left 62 people injured as stone-throwing mobs torched vehicles, underlining the turmoil gripping the Arab world's most populous nation.
Eight people were killed and hundreds more injured in clashes between rival demonstrators on December 5 outside Morsi's presidential palace in Cairo.
Some 250,000 police and soldiers were deployed to provide security during the referendum. The army has also positioned tanks around the presidential palace since early this month.
The main opposition group, the National Salvation Front, alleged in a statement that ballot fraud had taken place, citing reports of laymen posing as judges supposed to oversee the vote.
Morsi's vice president, Mahmud Mekki, whose post is not mentioned in the new charter, announced Saturday that he was resigning.
"Political work does not suit my professional character," he said in a statement, referring to his past as a respected judge.
State television reported that Central Bank chief Faruq El-Okda had also resigned, but later cited a cabinet source as denying this had happened.
A modest margin and a low turnout in the referendum is expected to embolden the opposition, which looks likely to continue its campaign against Morsi and his Muslim Brotherhood movement.
At one polling station in Giza, southwest Cairo, 50-year-old housewife Zarifa Abdul Aziz said: "I will vote 'no' a thousand times. ... I am not comfortable with the Brotherhood and all that it is doing."
However, 19-year-old law student Ahmed Mohammed said he voted "yes" because "Egypt needs a constitution to be stable."
Rights groups say the charter limits the freedoms of religious minorities and women, while allowing the military, which retains considerable influence over politics, to try civilians it believes "harm" the army.
Morsi had to split voting over two successive Saturdays after more than half of Egypt's judges said they would not provide the statutory supervision of polling stations.
The National Salvation Front launched a last-ditch campaign to vote down the charter after deciding that a boycott would be counter-productive.
Egyptian human rights groups also alleged that the first round was marred by fraud, setting up a possible later challenge to the results. The Front called news conferences for Sunday to give their observations on the second round.