CAIRO - A senior judge was sworn in as Egypt's interim president Thursday to replace ousted Islamist President Mohammed Morsi as the military launched a major crackdown against the Muslim Brotherhood.
Reeling from what it called a military coup against democracy, the group said it would not work with the new political system.
The sweep against the Brotherhood leadership included the group's top leader, a figure venerated among its followers, General Guide Mohammed Badie. He was arrested late Wednesday from a villa where he had been staying at a Mediterranean coastal city and flown by helicopter to Cairo, security officials said.
The move against the Brotherhood raises deep questions over how Islamists will fit into Egypt's new political system after the military on Wednesday swept out Morsi, the country's first elected president. The military is installing a new civilian leadership to pave the way to new elections, saying it will stay out of politics.
The army says it did so in the name of millions of Egyptians who had taken to streets demanding Morsi be removed.
In the eyes of protesters, Morsi and the Brotherhood from which he hails had warped the democratic process. Many say the group has proved its anti-democratic nature and argue that its leaders committed prosecutable crimes.
But the Brotherhood remains a powerful force, with a highly organized membership nationwide.
The top opposition political grouping, the National Salvation Front, issued a statement Thursday saying, "We totally reject excluding any party, particularly political Islamic groups."
The Brotherhood announced it wanted nothing to do with the new political system.
"We declare our complete rejection of the military coup staged against the elected president and the will of the nation," the Brotherhood said in a statement that the group's senior cleric, Abdel-Rahman el-Barr, read to Morsi's supporters staging a days-long sit-in in Cairo.
"We refuse to participate in any activities with the usurping authorities," it said.
There are fears of a violent backlash from Islamists against the army move, particularly from hard-liners, some of whom belong to former armed militant groups. Clashes between Islamists and police erupted in multiple places around the country after the army's announcement of Morsi's removal Wednesday night, leaving at least nine dead.
Morsi has been detained in an unknown location since the generals pushed him out. At least a dozen of his senior aides and advisers are being held in what is described as house arrest.
In the first step toward setting up a post-Morsi leadership, the chief judge of the Supreme Constitutional Court, Adly Mansour, took the oath as interim president before his fellow judges at the court.
After the ceremony aired live on state TV, Mansour delivered an address praising the massive street demonstrations that led to Morsi's ouster. He hailed the youth behind the protests that began June 30 and brought out millions around the country.
That day "corrected the path of the glorious revolution that took place on Jan. 25," he said, referring to the revolt against Hosni Mubarak that began Jan. 25, 2011, and led to his ouster 18 days later.