Supporters of Muslim Brotherhood presidential candidate Mohamed Morsi demonstrate in Cairo's landmark Tahrir Square
Tensions soared in Egypt on Saturday a day before the result of a divisive presidential election and as the Muslim Brotherhood sparred with the ruling generals over what it sees as a military power grab, reports AFP.
The electoral commission overseeing the divisive contest between Brotherhood candidate Mohamed Morsi and former Prime Minister, Ahmed Shafiq said it will announce the official winner on Sunday.
"Faruk Sultan, the head of the presidential election commission, will announce the results of the presidential election run-off on Sunday at 3:00pm (1300 GMT)," the commission's secretary general, Hatem Bagato, said in a statement.
Hundreds of Brotherhood supporters had spent the night in Cairo's iconic Tahrir Square, having vowed to stay there until the election result is published. By early evening, their numbers had swelled to thousands.
"Morsi, Morsi, God is the Greatest," the protesters chanted in anticipation of a victory for their candidate, who says tallies provided by electoral officials show that he won.
Both Morsi and Shafiq have claimed victory in the election for a successor to Hosni Mubarak, sparking tensions between the rival camps that have deepened after the electoral commission delayed announcing the official outcome.
Across the city, in the Nasr City neighbourhood, thousands of Shafiq supporters held up pictures of their candidate and of military ruler Field Marshal Hussein Tantawi, chanting "the people and the army are one."
"Down with the rule of the Supreme Guide," protesters shouted, referring to the head of the Muslim Brotherhood.
A massive security plan has been put in place in the capital to prevent unrest when the result is announced on Sunday, an interior ministry official told AFP.
The delay in the announcement of the result of the June 16-17 run-off, initially scheduled for Thursday, has raised suspicions that the outcome of the election is being negotiated rather than counted.
As the Supreme Council of the Armed Forces (SCAF) and the Brotherhood clashed publicly over recent measures that consolidated the army's power, privately they have been talking behind the scenes, sources told AFP.
On Friday, the SCAF warned it would deal "with utmost firmness and strength" with any attempts to harm public interests, while the Brotherhood warned against tampering with the election results but said it had no intention of instigating violence.
The Brotherhood rejects a constitutional declaration by the military which strips away any gains made by the Islamist group since the popular uprising which forced Mubarak to stand down in February last year.
The document dissolves the Islamist-led parliament and gives the army a broad say in government policy and control over the new constitution. It was adopted just days after a justice ministry decree granted the army powers of arrest.