Egyptian police said Friday a man died in clashes as tensions soared in Cairo following a bus bombing and further arrests of members of the Muslim Brotherhood after its listing as a terrorist group.
Defiant student supporters of the Brotherhood protested in Cairo on Thursday night, clashing with opponents of deposed Islamist president Mohamed Morsi in a flare up that left one person dead, the interior ministry said.
A Friday ministry statement added that seven Brotherhood supporters had been arrested after police intervened with tear gas.
The Islamists on Friday vowed to continue their protests, despite the ferocious crackdown on their movement.
"Let's begin with full force and peacefulness a new wave of majestic anti-coup action," said the Brotherhood-led Anti Coup Alliance in a statement.
Thursday's protests came hours after a bomb hit a bus in northern Cairo, wounding five people and prompting condemnation from US Secretary of State John Kerry.
State Department spokeswoman Jen Psaki said Kerry had also "expressed concern" about the Brotherhood's designation as a terrorist group, in a phone call with his Egyptian counterpart Nabil Fahmy.
The intensified crackdown on the Brotherhood, which prevailed in a series of polls held after the 2011 overthrow of Hosni Mubarak, came after the military-installed government blamed it for a suicide car bombing of police headquarters on Tuesday that was claimed by a jihadist group.
Kerry "underscored the need for an inclusive political process," Psaki said.
The explosion Thursday shattered the windows of a red and black bus as it passed near a busy intersection in the capital's Nasr City neighbourhood.
Construction worker Mahmud Abd al-Al described scenes of panic after the attack, saying the victims were "covered in blood" and that one man lost a leg.
The attack was "meant to terrorise people before the referendum," interior ministry spokesman Hany Abdel Latif told AFP.
The interim government has billed the referendum next month on a new constitution as the first step in a democratic transition ahead of parliamentary and presidential elections.
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Brotherhood faces harsh punishment
The Brotherhood's designation as a terrorist group carries harsh penalties and even less tolerance for its protests.
It could mean death sentences for Brotherhood leaders and five years imprisonment for participants in its protests, the interior ministry's Abdel Latif told state television.
The move caps a dramatic fall for the Brotherhood since Morsi was overthrown on July 3 amid massive protests demanding the Islamist's resignation.
The Brotherhood had since Morsi's overthrow been organising almost daily protests, despite the fact that more than 1,000 people, mainly Islamists, have been killed in street clashes in recent months and thousands more arrested, including the Brotherhood's top leadership.
On Thursday, Egyptian prosecutors ordered at least 18 Brotherhood members, including an ex-lawmaker, held on accusations of belonging to a terrorist group, state media reported.
Police also arrested 16 suspected members for passing out leaflets and "inciting the violence," it said.
Army chief General Abdel Fattah al-Sisi, who has ridden a wave of popularity since ending Morsi's divisive year-long rule on July, meanwhile vowed to eliminate terrorism as he urged Egyptians to trust the military in a fiery speech.
"Do not worry or fear, the army will sacrifice for Egypt. We will eliminate" terrorism, Sisi said at a military ceremony on Thursday.
The colonel general is widely expected to run in presidential elections amid a groundswell of support and widespread calls for a strong leader.
The Brotherhood renounced violence in the 1970s and condemned Tuesday's attack on a police headquarters north of Cairo, which was later claimed by a Sinai-based jihadist group called Ansar Beit al-Maqdis.
The Al-Qaeda inspired group has claimed some of the deadliest attacks in the Sinai that have killed more than 100 police and soldiers since Morsi's ouster.
Authorities say there are links between Ansar Beit al-Maqdis and the Muslim Brotherhood but have offered no proof.