Eight Egyptian rights groups have called for a repeat of the first round of voting in a constitutional referendum, citing widespread violations.
President Muhammad Morsi's Islamist allies say a majority of those who voted in the first round of a referendum on Egypt's disputed draft constitution -- nearly 57 percent -- endorsed the legislation.
The Cairo Institute for Human Rights Studies, one of the groups, told a news conference that alleged violations included preventing civil society observers from attending the vote counting, while allowing representatives of Morsi's Freedom and Justice Party.
It also cited religious propaganda, voting disruptions in some centers, and early closure of some polling stations.
Turnout was unofficially estimated at around 32 percent.
The December 15 vote, held in 10 provinces, came following weeks of mass street protests.
The second round takes place on December 22.
Based on reporting by Reuters and AP