Secular and Islamist opposition groups are boycotting the changes, saying they make it easier to rig future elections.

Correspondents say there has been little sign of the "millions of voters heading to ballot boxes" reported by the official news agency, Mena.

"What's the use? All referendums are fixed," said one taxi driver quoted by AFP news agency.

KEY AMENDMENTS

After almost two hours of voting at one Alexandria polling station, election officials are quoted as saying that 53 people out of more than 3,500 registered voters had voted.

Under Egyptian election laws, a low turn-out would not affect the outcome, as a simple majority of votes cast is required for victory.

The government says the changes will allow the drafting of a new anti-terrorism law to replace the emergency legislation in place since 1981, giving police wide powers of arrest and surveillance.

In addition, the amendments ban all religious-based political activity and parties, a blow to the already-banned Muslim Brotherhood, which represents the strongest opposition force.

They also allow the adoption of a new election law and do away with the need for judicial supervision of every ballot box.

Basic freedoms

Voting began at 0600 GMT, although a number of the country's 10,000 polling stations were reported to have opened late. About 36m people are registered to vote.