The first Egyptians to vote in a referendum on a controversial new constitution backed by President Mohamed Morsi and his Islamist allies have narrowly approved the document. The rest of Egypt's voters will cast their ballots next Saturday .

The president's Freedom and Justice Party and an opposition group, citing unofficial tallies, estimate 56 percent of voters approved the constitution in the first stage of the referendum Saturday.

The draft constitution has sparked weeks of violence and protests.

On Saturday, an opposition coalition accused the Muslim Brotherhood, which supports the proposed constitution, of rigging the vote. Mr. Morsi is a former member of the Muslim Brotherhood.

The vote has been staggered over two consecutive Saturdays due to a shortage of judges willing to oversee the voting.

It is not clear when final results will be announced.

Members of the liberal, secular and Christian opposition say they fear the constitution will erode civil liberties because it boosts the role of Islamic law and does not mention women's rights.

A largely Islamic committee approved the document last month after liberal and Christian members walked out, complaining they were being ignored.