The Egyptian government has intensified its crackdown on the Muslim Brotherhood, formally listing the group as a terrorist organisation.
It comes after the government accused the Brotherhood of carrying out a suicide bomb attack on a police station that killed 16 people.
The Brotherhood condemned the attack yesterday in the Nile Delta city of Mansoura, north of Cairo.
Earlier in the day, a Sinai-based militant group, Ansar Bayt al-Maqdis had claimed responsibility for the attack that wounded some 140 people.
The move gives the authorities the power to charge any member of deposed President Mohamed Mursi's movement with belonging to a terrorist group, as well as anyone who finances the group or promotes it "verbally, or in writing".
The Brotherhood, which was founded in 1928, was Egypt's best organised political force until this summer's crackdown. It estimates its membership at up to 1m people.
The government had said it would take harsh measures following the attack, which it said would not stop a political roadmap, whose first step before elections is a constitutional referendum due to be held in January.
The army deposed Mr Mursi in July following mass protests against his rule.
The government decision is the latest step in a crackdown that has put thousands of Brotherhood supporters in jail, including most of the group's top leadership.
Hundreds of Mursi supporters have been killed in the crackdown by security forces, and the group has already been banned by a court that ordered its assets to be seized.
Since Mr Mursi's downfall, at least 350 members of the security forces have been killed in bombings and shootings.
Ansar Bayt al-Maqdis, meaning 'Supporters of Jerusalem', has claimed responsibility for a number of the attacks since Mr Mursi's downfall, including a failed bid to kill the interior minister in September.
In its statement claiming responsibility for the Mansoura attack, Ansar Bayt al-Maqdis blamed the army-backed government for fighting "Islamic legitimacy" and spilling the blood of "oppressed Muslims".
Following yesterday's attack, Prime Minister Hazem el-Beblawi described the Brotherhood as a terrorist group, though today's move formalises the step.
"All of Egypt ... was terrified by the ugly crime that the Muslim Brotherhood group committed by blowing up the building of the Dakahlyia security directorate," an emailed statement from the interim government's cabinet office said.
"The cabinet decided to declare the Muslim Brotherhood group a terrorist organisation."
It reiterated past accusations against the group, including torturing people at protest camps set up after Mr Mursi's ouster and attacking churches.
In the last week, Mr Mursi and other top Brotherhood leaders have been charged with terrorism and plotting with foreign groups against Egypt, crimes that can carry the death penalty.
The Muslim Brotherhood renounced violence decades ago.