CAIRO — Egypt's Muslim Brotherhood decried a government order to enforce a court ruling designating the Islamist movement as a "terrorist" group."By this decision, the coup authorities seek to terrorize the Brotherhood and the free Egyptian people with the aim of forcing them to accept their usurped authority," the group said in a statement on Saturday.On Thursday, interim Prime Minister Ibrahim Mahlab issued an executive order to put into effect an earlier court ruling designating the Muslim Brotherhood as a "terrorist organization."Egypt's Court for Urgent Matters in February listed the Muslim Brotherhood – which propelled ousted president Mohamed Morsi to power in 2012 polls – as a "terrorist" organization.Egypt has been dogged by instability since the army unseated Morsi, the country's first freely elected president, in July following massive protests against his rule.Egyptian authorities have mounted a fierce crackdown on the Brotherhood, killing hundreds of supporters and arrested thousands.