CAIRO — Egypt’s military-backed leaders designated the Muslim Brotherhood a terrorist organization Wednesday, outlawing the country’s most successful political movement and vowing to treat anyone who belongs to it — or even takes part in its activities — as a terrorist.
Egypt’s leaders have been locked in conflict with the movement since July, when the military deposed Mohammed Morsi, Egypt’s first democratically elected president and a former Brotherhood leader.
The state’s security forces have killed hundreds of the movement’s supporters during protests against Morsi’s removal. Most of the Brotherhood’s leaders and thousands of its members have also been imprisoned.
With Wednesday’s decision, the government signaled its determination to cut off any air to the 80-year-old Islamist organization.
Analysts called it the most severe crackdown on the movement in decades, requiring hundreds of thousands of Brotherhood members to renounce the group or face prison, and granting the military and the police new authority to violently suppress the movement’s protests.
The decision could also outlaw hundreds of social and charity organizations run by Brotherhood members, and makes it a crime to promote the Brotherhood “by words.”
The decision came a day after officials blamed the Brotherhood for a suicide bombing at a police headquarters north of Cairo that killed 16 people, though Wednesday a separate group, Ansar Beit al-Maqdis, which has derided the Brotherhood for its lack of militancy, claimed responsibility for the bombing.
The government was not swayed. In announcing the terrorism designation, it again blamed the Brotherhood for the bombing of the police headquarters, without supplying evidence. Officials framed their decision as part of a decades-long struggle between the state and a militant movement.
It made no mention of the Brotherhood’s emergence after the fall of Egypt’s autocratic president, Hosni Mubarak, to become the most successful force in the country’s recent democratic elections.
“The Muslim Brotherhood remains as it was,” the Cabinet said in a statement. “It only knows violence as a tool.”
The designation represented a victory for government hard-liners who have pressed to eradicate the Brotherhood since the military’s ouster of Morsi in July. And it set Egypt, which has lurched from crisis to crisis over the last three years, on an even more precarious course.
Khalil al-Anani, a senior fellow at the Middle East Institute in Washington who studies the Brotherhood, called the designation “a turning point” in the conflict and said it could lead Egypt toward a civil conflict like the one that engulfed Algeria in the 1990s.
“This is a big miscalculation from the government,” he said. “It is a massive social movement, whose supporters might retaliate or fight back.”
With most of the Brotherhood’s senior leaders already imprisoned, he said, “there is a lack of communication between the leadership and young Brotherhood members. And these people can be dragged to the violent path.”
In September, a court ordered the dissolution of the Brotherhood and the confiscation of its assets; that move remains a preliminary injunction until a ruling from a higher court.
The focus on the Brotherhood appeared to distract the government from Ansar Beit al-Maqdis, a militant group inspired by Al Qaeda that has emerged as the face of a potent insurgency growing in sophistication and reach.
On Wednesday, the group claimed responsibility for the bombing of the police building in the city of Mansoura.
In a statement posted on online militant forums, the group also appeared to threaten similar attacks in the future, warning Egyptians to stay away from security buildings “to preserve your sacred lives and blood.”
The group, whose name means Supporters of Jerusalem, has orchestrated several of the most brazen attacks in a wave of assassinations and bombings targeting the security services since July.