Egypt's interim leader said a presidential election could be held before a parliamentary vote. Adly Mansour's comments raise the possibility that the country's military-backed government is preparing to deviate from the transitional plan it unveiled after ousting former president Mohammed Mursi in July. It also comes amid a widening crackdown on Mursi's Muslim Brotherhood, which was declared a "terrorist organisation" by the government last week. As the crackdown intensified, Egyptian secret police arrested an award-winning Australian journalist and an Egyptian reporter for the Qatar-based Al-Jazeera channel suspected of illegally broadcasting news harming "domestic security". The transitional plan had called for parliamentary elections to be held first, after a constitutional referendum. The government has emphasised its commitment to the transitional plan, offering it as evidence of its support for democracy. Analysts have said that switching the order of the elections could help Egypt's leaders maintain tighter control over the outcome, by allowing the newly elected president to influence the make-up of parliament, possibly by forming a political party. One of the most frequently mentioned candidates for president is defence minister General Abdel-Fattah el-Sisi. He has not said whether he would run. State media quoted Mansour, the interim president, as saying that holding the presidential vote first would be legal. The government announced it had designated the Brotherhood as a terrorist group after blaming it for a bombing that killed 16 people, despite another group claiming responsibility. Michael Wahid Hanna, a fellow at the Century Foundation in New York, said the government "seized on the moment and the grotesque nature of the attack" to accomplish several goals. While hardliners in the security services aimed to eradicate the Brotherhood, the terrorist designation gave other officials a "rhetorical" tool to stir interest in the coming elections, Hanna said. Al-Jazeera confirmed the arrests and said police also detained a producer and a cameraman. Officers of the National Security service raided the broadcaster's bureau at a Cairo hotel on Sunday, arresting two journalists and confiscating their equipment, the ministry said. Al-Jazeera English identified them as Cairo bureau chief Mohamed Adel Fahmy and Australian reporter Peter Greste.