Islamists backing a new constitution for Egypt claimed victory on Sunday in the first leg of a referendum, AFP reported.
Meanwhile, the opposition alleged polling violations and called for nationwide protests ahead of next weekend's second leg.
The two sides' positions drew out the deep uncertainty and division seen in Egypt over the past three weeks, a period marked by mass protests and deadly clashes.
A majority of 56.5 percent voted for the draft charter put to half of Egypt's 51 million voters on Saturday, according to the Freedom and Justice Party, the political branch of President Mohammed Morsi's Muslim Brotherhood.
Egyptian media reported roughly the same figure, which fell short of the landslide the Brotherhood had been hoping for to quiet the restive opposition.
The opposition National Salvation Front coalition said, meanwhile, it would "not recognize any unofficial result," and would wait for the formal tally after next Saturday's second round of voting.
The Front called on Egyptians to "take to the streets on Tuesday to defend their freedoms, prevent fraud and reject the draft constitution," according to AFP.
It reiterated its allegation that balloting had been "marred by irregularities and violations".
The head of the Front, Mohamed ElBaradei, a former chief of the UN nuclear energy agency, tweeted of the first round: "Country split, flagrant irregularities, low turnout, disillusion w(ith) Islamists on the rise. Illiteracy remains a hurdle."
Several Egyptian human rights and monitoring groups said there were irregularities and demanded Saturday's vote be done over.
They alleged monitors were excluded from some polling stations, judges were not present in all as required and some fake judges were seen, and women were prevented in some cases from casting their ballot.
Violence between the charter's supporters and opponents flared in Egypt's two largest cities, Cairo and Alexandria, just before and after the referendum, with police repelling an Islamist attack on the liberal Wafd party headquarters in the capital on Saturday night.
On December 5, clashes between pro- and anti-Morsi demonstrators outside the presidential palace killed eight people injured hundreds, prompting the army to deploy troops and tanks around the compound.
If the constitution is approved, Morsi hopes it will end a tumultuous transition almost two years after a popular uprising overthrew president Hosni Mubarak and ushered in interim military rule before Morsi's election in June.
Liberals and Christians had boycotted the assembly that drafted the charter, complaining the Islamist-dominated panel had ignored their concerns.
The key points of the controversial draft constitution are:
- Islam remains Egypt's official religion. The previous formulation that the "principles of sharia" are the main source of legislation is maintained.
However, these principles are broadened to include Sunni Muslim doctrinal interpretations.
- "Freedom of faith is guaranteed" -- but only for Islam, Christianity and Judaism, not for other religions.
- The president is limited to two consecutive four-year terms, not indefinitely as under Mubarak.
- The defense minister is chosen from within the military. Also, the military's budget will be decided by a committee dominated by military officers, effectively making it independent of civilian oversight.
- Civilians will not be tried in military courts except in cases where the "crimes may harm the armed forces." The opposition and rights groups demand that this vaguely defined exception be removed.
- The charter upholds "the equality of citizens under the law without discrimination," but omits an explicit mention of equality of the sexes.
- Freedom of expression is protected -- except when it comes to "insults against physical persons" or "insults towards the prophets." Some fear those exceptions open the door to censorship.
- The state is the designated protector of "public morals and order."
- It is forbidden for Egypt to sign international treaties and conventions that go against the constitution.