A retired army general with close ties to the military confirmed the report.
Hossam Sweilam said a panel of experts would draft a new constitution and the interim administration would be a presidential council led by the Supreme Constitutional Court's chief justice and including the defense minister, representatives of political parties, youth groups, Al-Azhar Mosque and the Coptic Church.
CAIRO -- Egypt's powerful military warned on Monday it will intervene if the Islamist president doesn't "meet the people's demands," giving him and his opponents two days to reach an agreement, as thousands of protesters massed for a second day calling on Mohammed Morsi to step down.
The 48-hour ultimatum, said the military, was a "last chance."
The military's statement, read on state television, puts enormous pressure on Morsi and his Muslim Brotherhood. So far, the president has vowed he will remain in his position, but the opposition and crowds in the street -- who numbered in the millions nationwide on Sunday -- have made clear they will accept nothing less than his departure and a transition to early presidential elections.
That makes military action when the deadline runs out nearly inevitable, since a deal seems unlikely. It did not define the "people's demands" that must be met. But it strongly suggested that Sunday's gigantic rallies expressed the desire of Egyptians, raising the likelihood it would insist on Morsi's departure.
Cheers erupted from many protesters watching the statement in Cairo's Tahrir Square as military helicopters buzzed overhead. "Come out, el-Sissi. The people want to topple the regime," protesters in the Nile Delta city of Mahalla el-Kubra chanted, urging military chief Gen. Abdel-Fattah el-Sissi to intervene.
Already, the military's presence in Cairo has increased at sensitive spots the past two days. Troops on Monday manned checkpoints on roads leading to a pro-Morsi rally of Islamists near his palace. They checked cars for weapons, after repeated reports some Islamists were arming themselves.
The military protests praised the anti-Morsi protests as "glorious," saying the participants expressed their opinion "in peaceful and civilized manner," and that "it is necessary that the people get a reply ... to their calls."
The military underlined it will "not be a party in politics or rule." But it said it has a responsibility to act because Egypt's national security is facing a "grave danger," according to the statement.
"The Armed Forces repeat its call for the people's demands to be met and give everyone 48 hours as a last chance to shoulder the burden of the historic moment," it said.
If the demands are not realized in that time, the military would be obliged to "announce a road-map for the future and the steps for overseeing its implementation, with participation of all patriotic and sincere parties and movements ... excluding no one."
The group that organized Sunday's mass rallies, Tamarod, issued an ultimatum of its own Monday, giving Morsi until the next day at 5 p.m. (1300 GMT) to step down or it would escalate its campaign with larger marches and "complete civil disobedience."
In a sign of Morsi's growing isolation, five Cabinet ministers met Monday to consider resigning their posts and joining the protest movement, the state news agency said. The meeting gathered the communications, legal affairs, environment, tourism and water utilities ministers, MENA reported.
Monday's statement was the military's second ultimatum. Earlier, el-Sissi gave the two sides a week to reach an agreement. That ultimatum expired on Sunday, with Morsi repeating his longstanding offer for dialogue, which the opposition rejected.
The swiftness of the military's new statement suggested it was prompted by the stunning turnout by the opposition on Sunday -- and the eruptions of violence that point to how the confrontation could spiral into chaos if it continues.
Sunday's protests were the largest seen in Egypt in the 2½ years of turmoil since the ouster of autocrat Hosni Mubarak in February 2011. Millions packed Cairo's Tahrir Square, the streets outside the Ittihadiya presidential palace and main squares in cities around the country on the anniversary of Morsi's inauguration.
The main rallies in Cairo were largely peaceful, but deadly violence broke out in several parts of the country, often when marchers came under gunfire, apparently from Islamists. At least 16 people were killed and more than 780 injured, Health Ministry spokesman Yehya Moussa told state television.
In Cairo, protesters Sunday night attacked the Brotherhood's main headquarters, pelting it with stones and firebombs. Brotherhood backers barricaded inside opened fire on them in clashes that went on for hours and left eight dead. In the early hours Monday, protesters breached the walls of the six-story luxury villa and stormed inside.
They carted off furniture, files, rugs, blankets, air conditioning units and portraits of Morsi, according to an Associated Press journalist at the scene. One protester emerged with a pistol and handed it over to a policeman outside.
Footage on local TV networks showed smashed windows, blackened walls and smoke billowing out of the fortified villa in the Muqattam district in eastern Cairo. A fire was still raging on one floor hours after the building was stormed. One protester tore down the Muslim Brotherhood sign from the building's front wall, while another hoisted Egypt's red, black and white flag out an upper-story window and waved it in the air in triumph.
Morsi's critics view the Brotherhood headquarters as the seat of real power in Egypt, consistently claiming that the Islamist group's spiritual leader, Mohammed Badie and his powerful deputy, Khairat el-Shater, actually call the shots behind Morsi. Morsi and Brotherhood officials have denied this and say they have tried to give opponents a greater voice, only to be spurned.
On Monday, anti-Morsi protesters were gearing up for a second day of demonstrations.
Some protesters spent the night in dozens of tents pitched in the capital's central Tahrir Square and in front of the president's Ittihadiya Palace. They have vowed to stay there until Morsi resigns. The president's supporters, meanwhile, continued their sit-in in front of a major mosque in another part of Cairo.
The anti-Morsi demonstrators are calling for widespread labor strikes in an attempt to ratchet up the pressure on the president, but it was not immediately clear whether unions would respond to the call. Organizers are also calling for sit-ins at the Cabinet building, interim parliament, and another presidential place where Morsi has been working since late last week instead of Ittihadiya.
Morsi has said he will not quit, saying that street action must not be allowed to remove an elected president or else the same could happen to future presidents. His Islamist supporters, some of them hard-liners who belong to formerly armed militant groups, have vowed to defend him. They showed Sunday they were willing to unleash deadly force when protesters approached their positions.
In its statement Monday, Tamarod, Arabic for "Rebel," called on the military and the police to clearly state their support for the protesters. Police mostly stayed on the sidelines Sunday, and some officers have vowed they will not protect the Brotherhood. The army has sent reinforcements to bases on the outskirts of Cairo and other cities across the nation and its Monday statement, in its entirety constitute clear support for Tamarod and the millions it brought out Sunday.
The military has for months been sending subtle but telling messages that it was not pleased with the policies pursued by Morsi and his Brotherhood.
Morsi was clearly scolding el-Sissi when he said in a televised address last Wednesday that the armed forces should focus on improving its capabilities.
The military seemed to reject that in its statement Monday, underlining that it "is a main player in the nation's future" and has "a national and historic duty to protect the security and safety of the nation."
For weeks, Morsi's supporters have depicted the planned protest as a plot by Mubarak loyalists to return to power. But their claims were undermined by the extent of Sunday's rallies. In Cairo and a string of cities in the Nile Delta and on the Mediterranean coast, the protests topped even the biggest protests of the 2011's 18-day uprising, including the day Mubarak quit, Feb. 11, when giant crowds marched on Ittihadiya.
The mood was largely festive as protesters at giant anti-Morsi rallies in Tahrir and outside the Ittihadiya palace spilled into side streets and across boulevards, waving flags, blowing whistles and chanting.
Fireworks went off overhead. Men and women, some with small children on their shoulders, beat drums, danced and sang, "By hook or by crook, we will bring Morsi down." Residents in nearby homes showered water on marchers below -- some carrying tents in preparation to camp outside the palace -- to cool them in the summer heat, and blew whistles and waved flags in support.
"Mubarak took only 18 days although he had behind him the security, intelligence and a large sector of Egyptians," said Amr Tawfeeq, an oil company employee marching toward Ittihadiya with a Christian friend. Morsi "won't take long. We want him out and we are ready to pay the price."
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