Egyptians voted on a constitution drafted by Islamists yesterday in a second round of balloting expected to approve a charter that opponents say will create deeper turmoil in the Arab world's most populous nation.

Islamist supporters of President Mohamed Mursi, who was elected in June, say the constitution is vital to move Egypt towards democracy two years after Hosni Mubarak was overthrown in a popular uprising. It will help restore the stability needed to fix an economy that is on the ropes, they say.

But the opposition says the document is divisive and has accused Mursi of pushing through a text that favours his Islamist allies while ignoring the rights of Christians, who make up about 10% of the population, as well as women.

As polling opened yesterday, a coalition of Egyptian rights groups reported a number of irregularities.

They said some polling stations had opened late, that Islamists urging a "yes" vote had illegally campaigned at some stations, and reported some voter registration irregularities, including the listing of one dead person.

The first round of voting last week resulted in a 57% vote in favour of the constitution, according to unofficial figures.

Analysts expect another "yes" because the vote covers rural and other areas seen as having more Islamist sympathisers. Islamists may also be able to count on many Egyptians who are simply exhausted by two years of upheaval.

If the basic law is passed, a parliamentary election will be held in about two months.

After the first round of voting, the opposition said a litany of alleged abuses meant the first stage of the referendum should be re-run.

But the committee overseeing the two-stage vote said their investigations showed no major irregularities in voting on December 15, which covered about half of Egypt's 51 million voters.

There was no indication yesterday that the alleged abuses were any worse than those claimed during the first round.

"I'm voting 'no' because Egypt can't be ruled by one faction," said Karim Nahas, 35, a stockbroker, at a polling station in Giza, a province which covers most of Cairo.

At another polling station, voters said they were more interested in ending Egypt's long period of political instability than in the Islamist aspects of the charter.

"We have to extend our hands to Mursi to help fix the country," said Hisham Kamal, an accountant.

Polling stations opened at 8am and closed at 7pm although voting could be extended.

Unofficial tallies are likely to emerge within hours of the close, but the referendum committee may not declare an official result for the two rounds until tomorrow.

Even if the charter is approved, the opposition says it is a recipe for trouble since it has not received broad-consensus backing from the population. They say the result may go in Mursi's favour but it will not be the result of a fair vote.

"I see more unrest," said Ahmed Said, head of the liberal Free Egyptians Party and a member of the National Salvation Front, an opposition coalition formed after Mursi expanded his powers on November 22 and then pushed the constitution to a vote.