Egypt brought forward the start of parliamentary elections to 22 April on Saturday to defuse a row with the Christian minority, who said the original schedule would conflict with their Easter celebrations.
Coptic Christians make up 10% of the population.
But the rift between Egypt's ruling Islamists and the opposition remained as deep as ever, with one leading liberal politician, Mohamed ElBaradei, saying he would boycott the polls.
The decision by Islamist President Mohamed Mursi to start the four-stage vote five days earlier than scheduled was announced by his spokesman on Facebook.
Islamists, who have won every election since the 2011 overthrow of autocrat Hosni Mubarak, dismissed any suggestion that the parliamentary polls would lack credibility and predicted a strong turnout.
Egyptian liberal opposition politician Mohamed ElBaradei this morning called for a boycott of parliamentary elections which start in April.
He said he refused to take part in "an act of deception".
Islamist President Mohammed Mursi called the elections on Thursday.
He hopes the elections will conclude Egypt's turbulent transition to democracy which began with the overthrow of autocrat Hosni Mubarak by popular protests.
But Mr ElBaradei, a former UN nuclear agency chief, noted that he had called in 2010 for a similar boycott of polls held under Mr Mubarak, who was ousted the following year.
"Today I repeat my call, (I) will not be part of an act of deception," Mr ElBaradei said on Twitter.
Islamists have used well-organised campaign operations to win every election since the revolution, while the liberal and leftist opposition has been beset by division.
The Muslim Brotherhood, which backs Mr Mursi, dismissed suggestions that the elections, to be held in four stages from April to June, would lack credibility.
Essam Erian, senior member of the Brotherhood's Freedom and Justice Party, said the polls would be carried out under "complete judicial supervision" as well as being followed by Egyptian, regional and international media.
Voting would also be monitored by Egyptian and foreign civil society and human rights organisations, he said on his Facebook page, adding that he expected wide participation.