Egypt to vote on divisive reforms
Egyptians are to vote in a referendum on a set of constitutional changes, which the opposition has criticised as paving the way for a police state.
The 34 amendments include a ban on the creation of political parties based on religion, and sweeping security powers.
The government says the changes will deepen democracy in the country and help it to fight terrorism.
Secular and Islamist opposition groups have called on their supporters to boycott the referendum.
If approved, 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.
They will ban the establishment of religious parties, allow the adoption of a new election law and do away with the need for judicial supervision of every ballot box.
Basic freedoms
President Hosni Mubarak and other government officials say the changes will give a boost to democratic practice in the country.
The BBC's Heba Saleh in Cairo says for many in the opposition this is a black day in Egypt's history as they say the changes spell the death of the constitution as the main guarantee of liberties and democracy.
The opposition says the changes will consolidate dictatorship, and that watering down judicial supervision of elections will make fraud easier.
They are also deeply uneasy about the wording of the articles on the new anti-terrorism law because it will be possible to bypass the constitutional guarantees protecting basic freedoms.
The new constitution appears designed to reverse the advances made in the last election by the Muslim Brotherhood, now the country's largest opposition force, our correspondent says.
Human rights group Amnesty International has called the changes the greatest erosion of human rights in 26 years.