Egyptians have approved the Islamist-drafted controversial constitution in the referendum, according to unofficial results.

Both supporters and opponents of President Mohammed Mursi have said that the constitution has been approved by the majority but official results are not expected until Monday.

Local media reports say nearly 64 percent of the electorate had cast their vote in favour of the referendum which the opponents say is based on the Islamic Sharia law. In the first phase of the referendum, the constitution is believed to have got the approval of 56 percent of the voters.

In the second phase, 17 provinces had voted under a security blanket involving at least 250,000 security personnel. Around 35 percent of the 25 million eligible voters turned up, claimed the ruling Muslim Brotherhood.

"According to our calculations, the final result of the second round is 71 percent voting 'yes' and the overall result (of the two rounds) is 63.8 percent," a Brotherhood official told Reuters.

The opposition has accused the Brotherhood of voting irregularities during both stages of the referendum and official results are likely to emerge after the appeals are heard.

Hours before closing of polling, former judge Vice President Mahmoud Mekky had stepped down saying the "nature" of politics does not go well with his judicial background.

Mursi's supporters and political groups are likely to be relieved over the results as protests over the constitutional draft had kept the Arab world's most populous nation on edge in the past few weeks. The referendum victory will be considered significant as the Islamist-led political groups in Egypt have proved their growing influence once again. Liberal groups which have been advocating a secular society, have been pushed to the background. The outcome of the referendum is also expected to lead to greater polarisation of various political formations.

The Islamists will now look forward to retaining power in the upcoming parliamentary elections which will take place soon after the election results.

The main opposition bloc, the National Salvation Front, is expected to hold a news conference later to outline its future strategy.

"Until now, the Supreme Electoral Commission has not investigated the violations committed in the first round. Will they investigate the irregularities after the announcement of the final result? A rigged referendum and invalid constitution," tweeted the well-known writer Alaa al-Aswany, who was once a strong supporter of Mursi.