Key Egyptian rights groups are calling for a repeat of the first round of a constitutional referendum on grounds that the vote was marred by widespread violations.
Representatives of the seven groups told a news conference that Saturday's vote in 10 of Egypt's 27 provinces lacked sufficient supervision by judges. They alleged that some individuals falsely identified themselves as judges, that vote counting was not witnessed by monitors and some women were prevented from voting.
The claim of widespread violations came only hours after President Mohammed Morsi's Muslim Brotherhood group claimed that a majority of Egyptians who voted on a proposed Islamist-backed constitution have approved the document.
Turnout was unofficially estimated at around 32%.
The second round of voting on the charter is planned for Saturday December 22.