Cairo (CNN) -- Egypt's interior ministry warned it would not tolerate any turmoil against authorities after Sunday's pivotal announcement of the country's new leader.
"Minister Mohamed Ibrahim has given police forces orders to shoot to kill against anyone attempting to attack police stations after the results," interior ministry spokesman Gen. Marwan Mustapha said. "Increased security has been dispersed in the side streets of (Cairo's) Tahrir Square to protect government buildings."
Egypt is set to declare the winner of its crucial presidential election at 3 p.m. (9 a.m. ET) Sunday, according to the Supreme Presidential Elections Commission.
But hours before the announcement, a former prime minister made a bold declaration on his Facebook page: "President Ahmed Shafik, Egypt 2012."
The claim of victory follows days of conflicting reports on who was leading the race and heightened concerns that Shafik, who served under ousted leader Hosni Mubarak, would give new life to the old guard and essentially nullify democratic gains won after last year's Egyptian revolution.
"Did we really have a revolution if Shafik wins?" prominent novelist Alaa al-Aswany said via Twitter. "For the thousandth time this is not a battle between the military and the (Muslim) Brotherhood, it is a battle of the Egyptian people with the military regime that ruled us with an iron fist for 60 years."
Like Mubarak, Shafik is a former air force officer with close ties to Egypt's powerful military and is "the quintessential candidate of the counter-revolution," said Khaled Elgindy, a visiting fellow at the Brookings Institution in Washington.
Shafik is running against Mohamed Morsi of the Freedom and Justice Party, the political arm of the Muslim Brotherhood. The election between Shafik and Morsi will determine Egypt's first democratically elected president.
On Saturday, authorities reviewed about 400 electoral violation reports submitted by the two candidates.
Ahead of the highly anticipated results, Egypt's all-powerful military leaders warned of potential chaos but said they won't reverse their widely deplored constitutional and judicial changes. They also warned politicians to keep a lid on election-related unrest.
"We will face anyone who will pose a challenge to the public and private sectors with an iron fist," the Supreme Council of the Armed Forces (SCAF) said.
Egypt's constitutional court dissolved the lower house of parliament this month, extending the military's power and sparking accusations of a coup d'etat.
Both presidential candidates claim victory in Egypt
Adding to the electoral tension is the question of how much power the new president will actually wield now that the military council has full legislative authority.
Under an interim constitutional declaration, the military council retains the power to make laws and budget decisions until a new constitution is written and a new parliament elected.
The declaration said Supreme Council members "shall decide all matters related to military affairs, including the appointment of its leaders." The president has the power to declare war, it says, but only "after the approval" of the Supreme Council.
The military council said it does not favor one political entity over another and respects the rights of Egyptians to protest but stressed the importance of self-restraint and respect for authority.
The Supreme Council urged political entities to respect democracy and "abstain from all possible acts that may descend the country into a full chaos."
Egyptian reform leader Mohamed ElBaradei -- the former head of the United Nations nuclear watchdog agency and a Nobel Peace Prize laureate -- said that if Shafik is declared the winner, "we are in for a lot of instability and violence ... a major uprising."
He said he isn't as worried about a Morsi victory because Shafik supporters are unlikely to take their anger to the streets.
ElBaradei described the current situation as "a total, complete 100% mess."
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